Green’s Dictionary of Slang

gander n.1

[reverse anthropomorphism]

1. a husband.

[UK]Satirist (London) 2 Dec. 390/2: ‘Philpotts, who, I see has got eighteen children, must be a powerful member of the new sect—in fact, I always thought him a proper-gander’.
[UK]Farmer & Henley Sl. and Its Analogues.
[Aus]Crowe Aus. Sl. Dict. 31: Gander, a married man.

2. (US) a man or husband who is away from home, a ‘grass-widower’.

[US]Matsell Vocabulum 36: gander A married man not living at home with his wife.
[US]Dly Dispatch (Richmond, VA) 1 Nov. 3/3: The detective [...] pointed out to the newspaper-man [...] a ‘gander,’ a married man.
[UK]Farmer & Henley Sl. and Its Analogues.
[US]E.S. Gardner ‘Leg Man’ in Ruhm Hard-Boiled Detective (1977) 216: You seem to think a middle-aged old gander is going to get a sweet, innocent girl to fall for just your own sweet self. Bunk!

In compounds

gander party (n.) (also gander-gang)

(US) a party for men only.

L.C. Bullard Now-a-Days 120: He was [...] quite the gentleman when he chose; the wildest and merriest at a gander party; the shrewdest and most far-seeing in business transactions.
Lowell Bigelow Papers 2 Ser. p. lviii: A few phrases not in Mr Bartlett’s book which I have heard [...] Gander-party: a social gathering of men only.
[US]Schele de Vere Americanisms 477: Gander-party is the modest name given occasionally in New England to what is more familiarly called a ‘stag-party,’ consisting of men only.
[US](con. 1828) G.W. Minns ‘Reminiscences of Boston Schools’ in Mass. Teacher 26 411: Remember, no woman was allowed to be present at this dinner [...] It was a ‘gander party,’ and even the boys were at a certain time turned out from it, in order that the men might sit and drink as much wine or other liquors as they pleased, smoke cigars, - and not blush for shame.
[US] Five Merry Girls 59: ‘It is a little out of the common run to call this a ‘gander party’, when it is composed entirely of young ladies. They usually apply that to a party of gentlemen’.
Farmer Americanisms: 259/1: gander-party.—A vulgarism for a party of men. Variants are gander-gang, stag-party.
[US]J. Maitland Amer. Sl. Dict.

SE in slang use

In phrases

gander-gutted (adj.)

US very thin.

[US]Gleaner (Manchester, NH) 30 Dec. n.p.: That long-legged, gander-gutted, sap-head.
[US]S.P. Avery Mrs. Partington's Carpet-bag of Fun 81: He put me in mind of a pair of kitchen tongs, all legs, shaft, and head, and no belly: a real gander gutted looking critter, as holler as a bamboo walking cane, and twice as yaller.