The word was used especially in reference to the characteristic meter of her poetry, and it was not until the 1890s that it gained its meaning of 'pertaining to sexual relations between women' the noun 'sapphism', meaning 'homosexual relations between women', also originated in the 1890s.
Sapphic as an adjective came into during the 16th century in reference to Sappho, poetess of the isle of Lesbos c.