Lesbian now means a female homosexual（同性恋者） or a woman who is primarily（天生） attracted to other women.The word used to mean the residents of the Isle（岛） of Lesbos, a Greek island, where lived a woman poet Sappho in 600 B. C.
Although much of her poetry had been destroyed by religious fundamentalists（原教旨主义者）, the few poems of Sappho that remain speak clearly her love and infatuation（迷恋） with women.
Being referred to as the tenth Muse by Plato, Sappho is the first lesbian ever documented. Prior to the word lesbian gaining popularity, women who loved other women were often called “sapphic”, and their love, defined as “sapphistry”.
The word gay, derived from the Old French word “gai”，originally means joyful or carefree, like the famous line in the poem Daffodils by William Wordsworth：“A poet could not but be gay in such a jocund company.”
It is around 1920s or 1930s that the word began to have a new meaning. A gay man is not just a man addicted to sexual pleasure, but a homosexual man.
It seems that the word homosexual is much too clinical（临床的）, suggesting a physical disorder, so the word gay is preferred for its association with mirth（欢乐） and freedom.
The abstract noun gaiety has largely cleared of the sexual connotation as with the word gay, and keeps its definition related to festive and celebration.