A metrical form invented by Sappho, the greatest of all poets. Also: relating to a form of quite nice naughtiness between consenting ladies, of which this poet Sappho of the isle of Lesbos was the most famous example in ancient times (her and her eager pupils, devotees of the love goddess Aphrodite), and therefore called both sapphism and lesbianism in her honour. It is sometimes doubted whether she was a small-l lesbian, but usually by people with an agenda. The evidence of her poems is not perhaps as physically explicit as the average Literotica story, but seems quite clear anyway.

In web searches, if you're actually looking for information about lesbians, the word 'sapphic' slightly improves your chances, since most hits for 'lesbian' actually mean 'big-haired prostitute with tongue pointing near naughty bits of another such a one'.