1. [early–mid-19C] a singer who opens their mouth wide.
2. [mid–late 19C] a herring; a sardine.
3. [mid-19C–1940s] a worthless, unpleasant person.
4. [mid-19C+] (Aus./US) an old and/or slow horse.
5. [late 19C+] (US) a native of Florida [the state’s indigenous animal].
6. [20C+] (US) any sexually aggressive male.
7. [1910s] (Aus.) an aggressive, tough person.
8. [1910s–70s] (US) a chatterbox, a ‘big mouth’.
9. [1930s–50s] a person, usu. non-black, who listens to and appreciates jazz, but does not play; orig. dismissive [the jazz musicians’ ref. to someone who ‘swallowed up’ everything on offer, ? coined by Louis Armstrong (1901–71) to describe white musicians who pirated the original ideas created by their black peers; ‘We’d call them alligators…because they were the guys who came to swallow everything we had to learn’].
10. [1950s] (US black) a white jazz musician [see sense 9].
11. [1950s] (US teen) any person, irrespective of musical taste.
12. see gator n.2 (2)
[1940s] (Aus.) nonsense, rubbish.
[1940s] (US drugs) a marijuana cigarette.
[19C] (US) a tough man, usu. used of a Kentucky frontiersman.
[late 19C] (Aus.) Queensland.
[1950s+] (US) a descriptive term for the mouth of a boaster, a braggart, someone with an inclination to boast or brag but insufficient courage to back up their words; such a person is usu. described in the extended phr. (he’s got) an alligator mouth and a hummingbird/canary ass; note don’t let your (alligator) mouth overload your ass(hole) under mouth n.
SE in slang uses
1. [late 19C-1960s] a black person, usu. a child [image of racist whites lynching blacks and tossing them to the alligators and f. the practice of Southern whites, who found it amusing to threaten such children with ‘throwing them to the alligators’].
2. [1900s–60s] (US) any inedible food, esp. liver [the practice in early 20C US construction camps of letting bull’s liver rot before cooking it; the meat was thus tenderized, but simultaneously rendered too foul for any human to eat].
3. [1910s–50s] (US) a worthless, unpleasant person, of any race.
4. [1940s] (US) a derog. term for a black native of Florida.
[1930s] (US black) don’t be slow(witted) or you will be out-done.