Bi-Lesbian

A bisexual lesbian (or bi-lesbian for short) is someone who is both bisexual and a lesbian.

This term can be used by women who use the split attraction model and are bisexual and homoromantic (lesbian) or someone who experiences lesbian tertiary attraction. They have sexual attraction to two or more genders but are only romantically attracted to women. They may find themselves sexually attracted to men, but could never picture themselves in a relationship with one, putting more emphasis on their attraction to women, though this varies from person to person.

It can also be used by people who identify as both bisexual and lesbian, either due to changing attraction (such as abrosexuality), or due being part of plural system (such as having a different sexuality when fronting, or being in a median system where you somewhat experience other headmates attractions.)

Additionally, the term can apply to women and other non-men who are bisexual and prioritize their attraction to women/non-men or have a strong preference for women/non-men, or for people who are reclaiming the historical definition of lesbian alongside identifying as bisexual.

Origins
The label "bi lesbian" originated in the 1970s as a result of the effects of lesbian separatism, a belief within some strains of lesbian feminism and often within radical feminism which advocates for separating women from men in as many ways as possible as a strategy to achieve women's liberation. Subsequently, this lead to lesbian separatists rejecting and often discriminating against women who refused to withdraw from their involvement with men, particularly bisexual women. Lesbian separatists accused bisexual women of "sleeping with the enemy" and forcefully removed them from lesbian spaces and from claiming the lesbian identity for themselves, by redefining it as "a homosexual female/woman" or "a woman who does not sleep with men/is not attracted to men". It is because of lesbian separatism that the bisexual label became very popular starting in the 1970s, as the word to describe a woman who was attracted to other women before was "lesbian", whether they were attracted exclusively or not, and now that had suddenly changed.

Examples of Use

 *  Lavender Woman, Volume 2, Issue 5, August 1973 : "What is a Lesbian? To me, a lesbian is a woman-oriented woman; bisexuals can be lesbians..."
 *  Lani Kaahumanu, "Bisexuality & Discrimination", BBWM Vol. 3, No. 6, Dec 1985-Jan 1986 : "...my lesbian awareness isn’t lost now that I claim my bisexuality [...] My political consciousness is lesbian but my lifestyle is bisexual..."
 *  Robyn Ochs, "Bi of the Month: Betty Aubut", Bi Women Vol. 5, No. 2, April-May 1987 : "I call myself a “bisexual lesbian.” I will always politically identify as bisexual, which to me means opposing restrictive categories [...] I consider myself gay. I think bisexuals are gay and gay liberation is our liberation..."
 * Amy Wyeth, "Don't Assume Anything", Bi Women Vol. 13, No. 4, Aug-Sep 1995: "Unfortunately, many of my experiences as a lesbian-identified bisexual woman have said to me that having an appearance or demeanor that diverges from the expected means I will not be accepted as truly belonging in the lesbian community."

Additional Sources

 * A Carrd site focussed on information on bi/mspec lesbians.
 * A Tumblr blog dedicated to sharing accurate and historically backed information about bi lesbians.