The word gay arrived in English during the 12th century from Old French gai, most likely deriving ultimately from a Germanic source.

In English, the word's primary meaning was "joyful", "carefree", "bright and showy", and the word was very commonly used with this meaning in speech and literature. For example, the optimistic 1890s are still often referred to as the Gay Nineties. The title of the 1938 French ballet Gaîté Parisienne ("Parisian Gaiety"), which became the 1941 Warner Brothers movie, The Gay Parisian, also illustrates this connotation. It was apparently not until the 20th century that the word began to be used to mean specifically "homosexual", although it had earlier acquired sexual connotations.

The derived abstract noun gaiety remains largely free of sexual connotations and has, in the past, been used in the names of places of entertainment, such as the Gaiety Theatre in Dublin.