4 × 4

or four-by-four

[ fawr bahy fawr, fohr bahy fohr, buh ]
/ ˈfɔr baɪ ˌfɔr, ˈfoʊr baɪ ˌfoʊr, bə /

noun

a four-wheeled automotive vehicle having four-wheel drive.
a piece of lumber approximately 4 inches thick by 4 inches wide.