tower (n.1)

Middle English tour, "building lofty in proportion to its base width," usually free-standing, often used as a fortification or prison, from Old English torr "tower, watchtower," from Latin turris "a tower, citadel, high structure" (also source of Old French tor, 11c., Modern French tour; Spanish, Italian torre "tower"), which is perhaps from a pre-Indo-European Mediterranean language.

The word in English was extended to any lofty pile or mass by mid-14c. It is also probably in part, from Old French tur. The modern English spelling with -w- is attested from c. 1400.

Often it is in specific reference to the Tower of London, which was The Tower by 1100. As a type of high headdress worn by women, c. 1600 (but the thing itself most popular at the end of that century).

c. 1400, "rise high, extend far up" like a tower (implied in towered); from tower (n.) in its later spelling. Also, of hawks, "fly high so as to swoop down on prey" (1590s), and, of larks "to soar in the act of singing" (1640s). Old English had torrien, torrian "stand high, tower."

"one who tows," 1610s, agent noun from tow (v.).