Watchtower
From BiblePortal Wikipedia
Holman Bible Dictionary [1]
2 Kings 9:17 Isaiah 5:2 Mark 12:1Tower
King James Dictionary [2]
WATCHTOWER, n. watch and tower. A tower on which a sentinel is placed to watch for enemies or the approach of danger.
Webster's Dictionary [3]
(n.) A tower in which a sentinel is placed to watch for enemies, the approach of danger, or the like.