MSM (Men Who Have Sex With Men) refers to a public health term used to describe males, regardless of their sexual orientation, who engage in sexual activity with other males. This term is used because it focuses on behavior rather than sexual identity or orientation. It encompasses those who identify as gay, bisexual, or heterosexual, and it is significant in discussions about sexual health, risk, and transmission of sexually transmitted infections (STIs). The usage of MSM helps in delivering targeted health messages and interventions without assuming or stigmatizing the sexual identities of the individuals.

MTF (Male-to-Female) is a term used to describe a transgender individual whose gender identity is female but was assigned male at birth. This term is part of the broader transgender spectrum and focuses on the gender transition from male to female, which may involve medical steps such as hormone therapy and surgery, but not necessarily. MTF is also referred to as a trans woman. This designation helps differentiate the specific experiences and needs of this group within the transgender community, particularly in contexts relating to healthcare, legal recognition, and social acceptance.

Magnetic often refers to a relationship where one partner is HIV-positive and maintaining an undetectable viral load through medication, while the other partner is HIV-negative. This term is derived from the idea of "magnetism" between opposites and highlights how advancements in HIV treatment and prevention have enabled serodiscordant couples (where one partner is HIV-positive and the other is HIV-negative) to have relationships with significantly reduced risk of HIV transmission. The concept supports the U=U (undetectable equals untransmittable) campaign, emphasizing that effective HIV treatment can prevent sexual transmission of HIV.

Malefail refers to a phenomenon within the transgender community, particularly among transgender women in the early stages of transition or before beginning transition, where attempts to present as male unintentionally fail. This often results from increasingly feminine physical features or mannerisms, which lead to being perceived by others as female, despite efforts to present as male. The term is generally used within the community to discuss experiences of gender presentation and can be a point of both challenge and affirmation of a transgender woman's identity.

Marriage within the LGBTQIA+ context refers to the legally or socially recognized union between two individuals of the same sex or gender identity. This definition expands the traditional notion of marriage to embrace same-sex couples, highlighting the movement towards equality and recognition of diverse relationships. The recognition of same-sex marriage has been a significant goal of LGBTQIA+ activism, reflecting broader struggles for civil rights, legal equality, and social acceptance.

The Marriage (Same Sex Couples) Act 2013 is a landmark law passed in England and Wales which legalized same-sex marriage. This legislation allows same-sex couples to legally marry in civil and religious ceremonies, where the religious institution consents. It represents a significant achievement in the fight for LGBTQIA+ rights, affirming the community's right to marriage equality. This act also allowed couples previously in civil partnerships to convert their union into a marriage and recognized overseas same-sex marriages as valid within England and Wales.

Marsha P. Johnson was a prominent figure in the LGBTQIA+ rights movement and is often remembered as one of the key leaders of the 1969 Stonewall uprising, a pivotal event that marked the beginning of the modern LGBTQIA+ rights movement in the United States. Johnson was a Black transgender woman known for her tireless activism and her role as a founding member of the Gay Liberation Front and co-founder of the Street Transvestite Action Revolutionaries (STAR), alongside Sylvia Rivera. Her advocacy was not only crucial in the fight for LGBTQIA+ rights but also highlighted the intersectional challenges faced by transgender people of color.

Mary is a term used as a playful or affectionate way to refer to each other. The term likely originated from the phrase "Mary, please," a sardonic retort to perceived dramatics or flamboyance, which became a shorthand for addressing or acknowledging gay men in conversation. It can express camaraderie, irony, or a shared understanding of common experiences within the community.

Masc, short for "masculine," refers to an identity or presentation typically associated with traditional masculinity within the LGBTQIA+ community, especially among gay and bisexual men. It is often used to describe individuals who exhibit physical, behavioral, or sartorial characteristics that align with societal norms of male masculinity. The term can also signify a preference in the context of attraction, where someone might specify an interest in partners who are "masc" or who embody masculine traits.

"Masc" in the context of women typically refers to a descriptor for women, often but not exclusively lesbian or queer, who present themselves in a masculine way. This can include attire, mannerisms, and other gender expressions that traditionally align with masculinity. "Masc" is often used within personal and social identity discussions to signal a departure from normative femininity and can help describe individual expressions of gender identity beyond binary categories.

"Masc for Masc" is a term used primarily in the gay community, often seen in dating and hookup app profiles. It describes a preference or expectation that potential partners or social interactions be with individuals who also exhibit traditionally masculine traits and behaviors. This term can sometimes be controversial as it may reflect underlying biases or exclusions based on gender expression or perceived femininity within the LGBTQIA+ community.

A "Masc Lesbian" refers to a lesbian who expresses themselves in a traditionally masculine way. This can include mannerisms, clothing choices, and personal grooming styles traditionally associated with men. Masc lesbians may identify with terms such as "butch" or "stud," which also connote a masculine presentation. This identity is about the expression of gender and does not necessarily relate to sexual orientation, as it is more about how individuals present themselves and are perceived in society and within the LGBTQIA+ community.

Masculine of Center (MOC) is a term used to describe individuals who express themselves in ways that align more closely with masculinity but do not necessarily identify as male. This can include, but is not limited to, women, non-binary individuals, and trans men who feel that their gender expression is primarily masculine but may not conform strictly to traditional male stereotypes. MOC is a broad, inclusive term that recognizes a spectrum of masculinity that can vary in presentation and identity, highlighting the diversity and complexity of gender expression.

A masochist is someone who derives pleasure, often sexual, from their own pain or humiliation. This term can intersect significantly with discussions around kink and BDSM (bondage, discipline, sadism, and masochism) communities. It is important to note that masochism within this framework is consensual and performed within the boundaries of pre-discussed limits and safe words. This expression of sexuality is recognized as part of the diverse spectrum of human sexual expression, particularly noted in discussions of sexual health, practices, and preferences within the community.

The Mattachine Society, founded in 1950 by Harry Hay among others, was one of the United States' first sustained gay rights groups. The name "Mattachine" is derived from the Societé Mattachine, a French society of masked dancers who used their performances to satirize social conventions and challenge societal norms. Inspired by this historical precedent, the American Mattachine Society aimed to address and dismantle the oppressive mechanisms of government, religion, and psychiatry against homosexuals. It played a crucial role in advocating for homosexual civil rights during a time when discrimination was widespread, employing a secretive cell-structure to protect its members. This society was foundational in the progression toward more public LGBTQIA+ advocacy efforts leading up to and beyond the Stonewall era.

Matthew Shepard was a young gay man whose tragic death in 1998 became a pivotal moment in American history, spotlighting the severe impact of hate crimes against LGBTQIA+ individuals. Shepard was brutally attacked and left for dead near Laramie, Wyoming, primarily because of his sexual orientation. His death galvanized advocacy efforts, leading to increased awareness and legislative action against hate crimes, including the Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act signed into law in 2009. Shepard's story remains a critical part of LGBTQIA+ history, symbolizing the ongoing fight against homophobia and the quest for equality and justice within the community.

The Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act, enacted in 2009, is a significant United States law that expands the 1969 U.S. federal hate crime law to include crimes motivated by a victim's actual or perceived gender, sexual orientation, gender identity, or disability. Named after Matthew Shepard, a young gay man murdered in 1998, and James Byrd Jr., an African American man brutally killed in 1998, the law aims to address and prevent hate crimes in America. This act allows federal authorities greater ability to engage in hate crimes investigations that local authorities choose not to pursue and provides $5 million per year in funding for fiscal years 2010 through 2012 to help state and local agencies pay for investigating and prosecuting hate crimes.

The Matthew Shepard Foundation is a nonprofit organization dedicated to honoring the life of Matthew Shepard, a young gay man whose brutal murder in 1998 became a pivotal moment in the modern LGBTQ+ rights movement. Founded by Judy and Dennis Shepard, Matthew's parents, the foundation aims to replace hate with understanding, compassion, and acceptance through various educational, outreach, and advocacy programs. It focuses on eradicating hate crimes and engaging youth and educators in dialogue about inclusivity and equality.

The Maverique Pride Flag represents the identity of maverique individuals within the LGBTQIA+ community. Maverique is a non-binary gender identity that is defined not by masculinity or femininity, but by its own unique characteristics of autonomy and inner conviction regarding a sense of self that is independent of male and female gender norms. This identity challenges traditional gender binaries and emphasizes a personal, internal experience of gender that is unrelated to the common gender spectrum. The flag itself features colors specifically chosen to represent maveriqueness: yellow to symbolize the unique nature of the identity, white for agender or gender neutrality, orange for the individuality, and black representing autonomy from the traditional gender binary.

The "Meat Rack" is a term used to describe a specific area located between Fire Island Pines and Cherry Grove. It is a wooded section on the bay side of the island, known as a notable spot for cruising and engaging in sexual activities in a public but relatively secluded setting. The area is recognized as a place where individuals can explore their sexuality freely and safely. It has cultural significance in the LGBTQIA+ community, having been featured in various books and movies, and is also informally known as the Judy Garland Memorial Path.

Medical transition refers to the process through which transgender and non-binary individuals alter their physical bodies through medical means to better align with their gender identity. This can include hormone replacement therapy (HRT), various forms of surgery such as top surgery (breast augmentation or removal) and bottom surgery (altering genitalia), and other medical procedures like facial feminization surgery or voice modification surgeries. Medical transition is a deeply personal journey, varies greatly between individuals, and not all transgender or non-binary people choose to undergo medical transitions.

Mephedrone, also known by street names such as Meph, M-Cat, and Meow-Meow, is a synthetic stimulant drug of the amphetamine and cathinone classes. It is known for its effects similar to those of MDMA (ecstasy) and cocaine. Mephedrone became popular in the late 2000s, especially within various nightlife and party scenes, including those frequented by some within the LGBTQIA+ community. The substance can provide heightened feelings of euphoria, openness, and sociability which may enhance social interaction and communal experiences at gatherings or clubs. However, it also poses significant health risks including addiction, severe physical side effects, and adverse mental health effects.

Metrosexual is a term that emerged in the early 2000s to describe a heterosexual man with a strong concern for his appearance or lifestyle, often embodying traits traditionally associated with homosexual men. This includes a keen interest in fashion, grooming, and aesthetics. The term is broadly used within popular culture and can sometimes be seen in discussions about gender expression and identity. It highlights how individuals may transcend traditional gender norms through their self-presentation and lifestyle choices, regardless of their sexual orientation.

Microaggressions are subtle, often unintentional, expressions of prejudice or insensitivity towards members of marginalized groups, including those based on sexual orientation, gender identity, race, and other aspects of identity. Within the LGBTQIA+ community, these can manifest as comments or actions that undermine and invalidate the experiences or identities of LGBTQIA+ individuals. Examples include assuming all individuals adhere to traditional gender roles, using incorrect pronouns after being corrected, or making dismissive statements about the legitimacy of non-binary identities.

The term "military" in LGBTQIA+ kink contexts refers to a fetish or sexual fantasy that involves military uniforms, scenarios, or power dynamics inspired by military settings. This can include role-playing involving authority figures like soldiers or officers, and the use of military apparel or symbols in BDSM practices. Participants may find the structured hierarchy and discipline of military-like scenarios erotic and engaging, incorporating these elements into their sexual expression and identity.