gaol

[See Jail.]
A place of confinement, especially for minor offenses or provisional imprisonment; a jail. [Preferably, and in the United States usually, written jail.]

Commission of general gaol delivery, an authority conferred upon judges and others included in it, for trying and delivering every prisoner in jail when the judges, upon their circuit, arrive at the place for holding court, and for discharging any whom the grand jury fail to indict. [Eng.] -- Gaol delivery. (Law) See Jail delivery, under Jail.

The old English word for jail.

The noun has one meaning:

Meaning #1: 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

The verb gaol has one meaning:

Meaning #1: lock up or confine, in or as in a jail
  Synonyms: imprison, incarcerate, lag, immure, put behind bars, jail, jug, put away, remand