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.).

c. 1600, figurative, "rising to a high pitch or intensity," present-participle adjective from tower (v.). The literal sense of "very high or lofty" is attested by 1630s. Related: Toweringly.

symbol of artistic or intellectual aloofness, by 1889, from French tour d'ivoire, used in 1837 by critic Charles-Augustin Sainte-Beuve (1804-1869) with reference to the poet Alfred de Vigny (1797-1863), whom he accused of excessive aloofness.

Et Vigny, plus secret, comme en sa tour d'ivoire, avant midi rentrait. [Sainte-Beuve, "Pensées d'Août, à M. Villemain," 1837]

Used earlier as a type of a wonder or a symbol of "the ideal." The literal image is perhaps from Song of Solomon [vii:4]:

Thy neck is as a tower of ivory; thine eyes like the fishpools in Heshbon, by the gate of Bathrabbim: thy nose is as the tower of Lebanon which looketh toward Damascus. [KJV]

"tower containing a clock," usually a large one with dials exposed on all four sides, 1757, from clock (n.1) + tower (n.). Older words for this were clocher (14c., from Old French), belfry.

erected in the Champ-de-Mars for the Paris Universal Exposition of 1889; at 984.25 feet the world's tallest structure at the time. Designed by French engineer Alexandre Gustave Eiffel (1832-1923).

c. 1300, touret "small tower forming part of a city wall or castle," from Old French torete (12c., Modern French tourette), diminutive of tour "tower," from Latin turris (see tower (n.1)). Meaning "low, flat gun-tower on a warship" is recorded from 1862, later also of tanks. Related: Turreted. Welsh twrd is from English.

"high, rocky hill," Old English torr "rock, crag" (said to be a different word from torr "tower"); from a Celtic source cognate with Gaelic torr "lofty hill, mound," Old Welsh twrr "heap, pile;" and perhaps ultimately with Latin turris "high structure" (see tower (n.)). But sources disagree on whether the Celts borrowed it from the Anglo-Saxons or the other way. English tore "projecting ornament" (1550s) also might be related.

also watch-tower, 1540s, from watch (v.) + tower (n.).