Easton's Bible Dictionary
Moved on pivots of wood fastened in sockets above and below (Proverbs 26:14). They were fastened by a lock (Judges 3:23, 25; Cant. 5:5) or by a bar (Judges 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 (Exodus 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 Corinthians 16:9; 2 Corinthians 2:12; Colossians 4:3). Our Lord says of himself, "I am the door" (John 10:9). John (Revelation 4:1) speaks of a "door opened in heaven."