Boyd’s Bible Dictionary:
(shot up). Watchtowers, or fortified posts, were frequent on frontiers and exposed places (Gen. 35:21; 2 Chron. 26:10); around vineyards (Isa. 21:5,8,11; Matt. 21:33), and for the use of shepherds (Mic. 4:8). “Tower of Shechem” (Judg. 9:47), evidently a citadel or stronghold. Tower of Babel [BABEL]. “Tower of Siloam,” possibly an observatory (Luke 13:4).
Concise Bible Dictionary:
Often referred to in scripture as a place of security, and also as a place of defense, on which watchmen were stationed. There were such on the walls of Jerusalem (Psa. 48:12; Psa. 61:3; 2 Kings 9:17). The term is also used symbolically: “the name of Jehovah is a strong tower” (Prov. 18:10).
Strong’s Dictionary of Greek Words:
Meaning:
apparently a primary word ("burgh"); a tower or castle