Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Moved on pivots of wood fastened in sockets above and below (Pr. 26:14). They were fastened by a lock (Judg. 3:23, 25; Song 5:5) or by a bar (Judg. 16:3; Job 38:10). In the interior of Oriental houses, curtains were frequently used instead of doors.
The entrances of the tabernacle had curtains (Ex. 26:31-33, 36). The "valley of Achor" is called a "door of hope," because immediately after the execution of Achan the Lord said to Joshua, "Fear not," and from that time Joshua went forward in a career of uninterrupted conquest. Paul speaks of a "door opened" for the spread of the gospel (1 Cor. 16:9; 2 Cor. 2:12; Col. 4:3). Our Lord says of himself, "I am the door" (Jn. 10:9). John (Rev. 4:1) speaks of a "door opened in heaven."