Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Used to denote the means by which a door is bolted (Neh. 3:3); a rock in the sea (Jonah 2:6); the shore of the sea (Job 38:10); strong fortifications and powerful impediments, etc. (Isa. 45:2; Amos 1:5); defences of a city (1 Ki. 4:13). A bar for a door was of iron (Isa. 45:2), brass (Ps. 107:16), or wood (Nah. 3:13).