gaol (n.)

see jail (n.), you tea-sodden football hooligan. Formerly in official use in Britain, and thus sometimes regarded in U.S. as a characteristic British spelling (though George Washington used it); by the time of OED 2nd edition (1980s) both spellings were considered correct there; the g- spelling is said to have been dominant longest in Australia.

[T]he very anomalous pronunciation of g soft before other vowels than e, i, & y ... is a strong argument for writing jail [Fowler]

updated on September 25, 2018

Definitions of gaol from WordNet
gaol (v.)
lock up or confine, in or as in a jail;
Synonyms: imprison / incarcerate / lag / immure / put behind bars / jail / jug / put away / remand
gaol (n.)
a correctional institution used to detain persons who are in the lawful custody of the government (either accused persons awaiting trial or convicted persons serving a sentence);
Synonyms: jail / jailhouse / clink / slammer / poky / pokey
From, not affiliated with etymonline.