n. One who tests, tries, assays, or proves.n. Any instrument or apparatus used in testing: as, a steam-gage tester; a vacuum-tester.n. A canopy.n. Specifically— The frame which connects the tops of the posts in a four-post bedstead, and the material stretched upon it, the whole forming a sort of canopy.n. In architecture, a flat canopy, as over a pulpit or a tomb.n. A head-piece; a helmet.n. A name given to the shillings coined by Henry VIII., and to sixpences later (compare teston); also, in modern slang, a sixpence.