Green’s Dictionary of Slang

1. drunk and incapable [link to fluff v.¹ (2)].

1899		London Standard 12 Apr. 8/2: Sometimes so happens that the Major’s fluffy when I get back .
1984		Partridge DSUE (8th edn) 411/1: ca. 1885.

2. gentle, unaggressive, sympathetic.

1918		R.H. Knyvett ‘Over There’ with the Australians 19: Some girl must have jilted him, and this was his revenge on the fluffy things.
1927		H.C. Witwer Classics in Sl. 14: I’m sick of them fluffy dames which is sweet and soft like a cream puff and yells murder when they see a mouse.
1944		C.B. Davis Rebellion of Leo McGuire (1953) 253: As a boy Johnny seemed to prefer fluffy muffs.
1998		L. Stringer Grand Central Winter (1999) 91: She whips up a page and a half of cute, sweet, and fluffy copy. Only I hate cute and sweet. And I’ll chew ground glass before I put up with fluffy.
2000		Indep. on Sun. Culture 7 May 4: She is supposed to be by turns [...] dippy, fluffy, kooky and feisty.

3. (US gay) of a lesbian, sexually excited.

1999

Gaymart.com Queer Sl. in the Gay 90s 🌐 Fluffy – Term used by lesbians. Meaning – a woman is turned on.

4. (US gay) among leather-wearing homosexual men, refusing to accept the dress-code.

1999

Gaymart.com Queer Sl. in the Gay 90s 🌐 Fluffy In gay male leather circles, this term is meant for someone who isn’t into the dress code. Derives from the description of someone who wears bulky or ‘fluffy’ sweaters. A putdown from a leather man might be: ‘You look awfully fluffy tonight’.