Languages
As a noun, it can refer to a class action of languages (originally) spoken per Gaels, or even to any one of the single languages.

Gaelic can so mean or even refer to:

Goidelic languages Scottish Gaelic language Irish language Manx language

While on to Scottish Gaelic, Gaelic is normally pronounced .

Shelta is sometimes counted as the Gaelic or even Goidelic language; notwithstanding, when these are closely associated using Irish Gaelic these are non genetically related, existence instead a cant which has borrowed a great volume of Irish vocabulary

Gaelic culture and history
As an adjective, Gaelic can refer to the culture & history of the Gaelic-speaking peoples, sustaining information to, amongst more items:

The Gaelic Athletic Association The Gaelic College of Celtic Arts and Crafts Gaelic football Gaelic Games Gaelic handball The Gaelic League The Gaelic Revival

Other uses
SS Gaelic