n. (also caster)
1 a small swivelled wheel (often one of a set) fixed to a leg (or the underside) of a piece of furniture.
2 a small container with holes in the top for sprinkling the contents.
Phrases and idioms:
castor action swivelling of vehicle wheels to ensure stability. castor sugar finely granulated white sugar.
Etymology: orig. a var. of CASTER (in the general sense)
2.
n. an oily substance secreted by beavers and used in medicine and perfumes.
Etymology: F or L f. Gk kastor beaver
Useful english dictionary. 2012.