The digit or figure 6.
(by ellipsis of six o'clock) Rear, behind (rear side of something).
cover my six
An event whereby a batsman hits a ball which does not bounce before passing over a boundary in the air, resulting in an award of 6 runs for the batting team.
A touchdown.
Small beer sold at six shillings per barrel.
A pair of sixes.
Short for six of one, half a dozen of the other.