|1.||a tall, usually square or circular structure, sometimes part of a larger building and usually built for a specific purpose: a church tower; a control tower|
|2.||a place of defence or retreat|
|3.||a mobile structure used in medieval warfare to attack a castle, etc|
|4.||tower of strength a person who gives support, comfort, etc|
|5.||(intr) to be or rise like a tower; loom|
|[C12: from Old French tur, from Latin turris, from Greek]|
tower of strength
A dependable person on whom one can lean in time of trouble, as in After Dad died Grandma was a tower of strength for the whole family. This expression, first recorded in 1549, originally was used most often to refer to God and heaven, but Shakespeare had it differently in Richard III (5:3): "Besides, the King's name is a tower of strength."