Green’s Dictionary of Slang

1. (US) a girlfriend, a female companion.

1895		Fort Worth Gaz (TX) 5 May 3/5: There was Katy Reilly, a pretty girl that ‘Bug’ Connors called his ‘rag’.
1900		A.H. Lewis ‘Joe Dubuque’s Luck’ in Sandburrs 152: She’s a bute, Joe’s Rag is.
1904		St Paul Globe (MN) 7 Aug. 27/2: ‘She’s a Romeo rag-ga, ain’t ta it?’ protested ‘Lamps’, the ‘Dago’, a handsome Italian boy with notable black eyes [...] ‘Cert. Whose rag is she den. She’s his’n’.
1910		H. Hapgood Types from City Streets 320: She [...] knocked a cigaret out of a rag’s hand w’at was holding it fer a bloke.
1926		Wood & Goddard Dict. Amer. Sl. 42: rag. A woman; a piece of jazz music.
1931		Irwin Amer. Tramp and Und. Sl. 154: Rag. –[...] A woman. [...] contemptuous; but with no regard to the appearance or the financial situation or standing of the woman.
1949		Monteleone Criminal Sl. (rev. edn) 188: rag A woman or girl [...] rag and bone A woman or girl.
1962		Ragen & Finston World’s Toughest Prison 814: rag – A woman.
1972		B. Rodgers Queens’ Vernacular 167: rag [...] 2. (pej) any woman representing a threat to a gay boy.

2. (US campus) an unattractive female.

1966		Current Sl. I:3 6/2: Rag, n. An unattractive or dull girl.
1967–8		Baker et al. CUSS.

3. (Aus.) a promiscuous woman.

1979

Lette & Carey Puberty Blues 115: She doesn’t hit up you know. She just scratches herself and coughs, the rag.