Green’s Dictionary of Slang

1. a landlady.

1884

Sporting Times 11 Oct. 2/2: The dowagers, whom it is now the swagger thing to call one’s landlady.

2. (gay) an elegant, older, gay man.

1937		L.A. Times 7 Jan. 6/1: A male cream-puff with a baby-pink muffler [...] squeals ‘Bravo, bravo’ [...] then, answering the disapproving frowns of surrounding dowagers he cries [etc].
1941		G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
1965		Guild Dict. Homosexual Terms 12: dowager (n.): A well-to-do, elderly homosexual. A variation of Auntie (q.v.) which can have some connection in the heterosexual world, for a Dowager can mean a Widowed Aunt. (Rare.).
1972		B. Rodgers Queens’ Vernacular.
2003		K. Cage Gayle.