Tower
Old English torr, reinforced in Middle English by Old French tour, from Latin turris, from Greek.
wiktionary
From Middle English tour, tur, tor, from Old English tūr, tor, torr("tower; rock"; > English tor) and Old French tour, toer, tor; both from Latin turris(“a tower”).
Compare Scots tour, towr, towre(“tower”), West Frisian toer(“tower”), Dutch toren(“tower”), German Turm(“tower”), Danish tårn(“tower”), Swedish torn(“tower”), Icelandic turn(“tower”), Welsh tŵr. Doublet of tor.
From Middle English touren, torren, torrien, from Old English *torrian, from the noun (see above).
From tow + -er.
etymonline
tower (n.1)
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"), possibly from a pre-Indo-European Mediterranean language. Meaning "lofty pile or mass" is recorded from mid-14c. Also borrowed separately 13c. as tour, from Old French tur; the modern spelling (1520s) represents a merger of the two forms.
tower (v.)
c. 1400, "rise high" (implied in towered); see tower (n.). Also, of hawks, "to fly high so as to swoop down on prey" (1590s). Related: Towering.
tower (n.2)
"one who tows," 1610s, agent noun from tow (v.).
