'Spray gun' definitions:

Definition of 'spray gun'

noun

An applicator resembling a gun for applying liquid substances (as paint) in the form of a spray

From: GCIDE

Spray gun \Spray" gun`\ (spr[=a]"g[u^]n`), n. a container for liquid, fitted with a conduit that can be supplied with compressed air, desiged to allowing the contents to be sprayed as an aerosol. Such devices are used to spray paints and various other liquids. [PJC]