Green’s Dictionary of Slang

1. (US) an older woman who keeps a (usu.) younger lover.

1926		Judge (NY) 91 July-Dec. 31: Sugar Mamma - Sweet on all the boys.
1979		‘Iceberg Slim’ Airtight Willie and Me 165: She went to the juke box [...] pursued by a derelict roue in quest of a sugarmama.
2011		J.J. Connolly Viva La Madness 12: All the decent bartenders and waiters were hunting for sugar mamas — who they’d fuck delirious.
2012		Courier-Mail (Brisbane) 18 May 🌐 She falls in with a group of ‘sugar mamas,’ fellow middle-aged women who feel neglected at home and seek the attention of much younger local men in exchange for cash.
2012		Topix Local News (Johannesburg) 14 Nov. 🌐 Am 27 years old [...] looking for a loving sugar mama.
2012		Topix Local News (Johannesburg) 29 Dec. 🌐 I’m looking for a sugar mom [...] a sugar mom who is rich.
2020		S.A. Crosby Blacktop Wasteland 83: ‘Tell your sugar mama I said hi’.

2. (US gay) an effeminate older gay man providing material support for his younger lover; cit. 1972 refers to a man although uses a female pronoun.

1972		B. Rodgers Queens’ Vernacular 191: sugar mama effeminate homosexual who keeps her lover.
1988		H. Max Gay (S)language.
2004		Sun. Indep. (Dublin) Living 26 Sept. 8/1: I’ve decided i need to get me a Sugar Mama and have someone else pick up the cheque.