"Gaol" is a decreasingly popular, but still quite valid(*),
alternative spelling of "jail" in UK, Ireland and Australia.  See for
example the brief discussion on http://en.wiktionary.org/wiki/gaol

(*) Indeed, some view "gaol" as the "more correct" British spelling of
the US-ified "jail".


% echo gaol | ispell -dbritish -a
@(#) International Ispell Version 3.3.02 12 Jun 2005
*

(ie: gaol is a recognised word by ispell)


% echo gaol | aspell -dbritish -a
@(#) International Ispell Version 3.1.20 (but really Aspell
0.60.7-20110707)
& gaol 9 0: goal, Gail, gal, GAO, AOL, Gael, Gall, Gaul, gall

(ie: gaol is not a recognised word by aspell, and here's a list of
suggestions)


 - Gus