Etymology
Advertisement
B.T.U. 

1889 as an abbreviation of British Thermal Unit (1862), a commercial unit of electrical energy (the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit); the French Thermal Unit is the amount of heat required to raise 1 kilogram of water 1 degree centigrade. Also from 1889 as an abbreviation of Board of Trade Unit, in electicity "1,000 watt hours."

Related entries & more 
Advertisement
relieve (v.)

late 14c., releven, "alleviate (pain, etc.) wholly or partly, mitigate; afford comfort; allow respite; diminish the pressure of," also "give alms to, provide for;" also figuratively, "take heart, cheer up;" from Old French relever "to raise, relieve" (11c.) and directly from Latin relevare "to raise, alleviate, lift up, free from a burden," from re-, here perhaps an intensive prefix (see re-), + levare "to lift up, lighten," from levis "not heavy" (from PIE root *legwh- "not heavy, having little weight").

The notion is "to raise (someone) out of trouble." From c. 1400 as "advance to the rescue in battle, bring help to a besieged place;" also "return from battle; recall (troops)." Meaning "release from duty" is from early 15c. Related: relieved; relieving.

Related entries & more 
levee (n.1)
1719, "natural or artificial embankment to prevent overflow of a river," from New Orleans French levée "a raising, a lifting; an embankment," from French levée, literally "a rising" (as of the sun), noun use of fem. past participle of lever "to raise," from Latin levare "to raise, lift up; make lighter" (from PIE root *legwh- "not heavy, having little weight"). They also were used as landing places.
Related entries & more 
heighten (v.)
mid-15c., heightenen, transitive, "to exalt, to honor or raise to high position," from height + -en (1). Intransitive sense of "to become higher" is from 1560s. Related: Heightened; heightening.
Related entries & more 
hunch (v.)
"raise or bend into a hump," 1650s; earlier "to push, thrust" (c. 1500), of unknown origin. Perhaps a variant of bunch (v.). Related: Hunched; hunching.
Related entries & more 
Advertisement
elevation (n.)

late 14c., "a rising, height of something, height to which something is elevated," from Old French elevation and directly from Latin elevationem (nominative elevatio) "a lifting up," noun of action from past-participle stem of elevare "lift up, raise," figuratively, "to lighten, alleviate," from ex "out" (see ex-) + levare "to lighten; to raise," from levis "light" in weight (from PIE root *legwh- "not heavy, having little weight"). Meaning "act of elevating" is from 1520s.

Related entries & more 
roust (v.)

"raise or arouse, stir up" (from one's bed, etc.), 1650s, probably an alteration of rouse with excrescent -t. Related: Rousted; rousting.

Related entries & more 
alert (adv.)

"on the watch," 1610s, from French alerte "vigilant" (17c.), from prepositional phrase à l'erte "on the watch," from Italian all'erta "to the height." Second element from erta "lookout, high tower," noun use of fem. of erto, past participle of ergere "raise up," from Latin erigere "raise" (see erect (adj.)).

The adjective is attested from 1712; the noun is from 1796 as "attitude of vigilance" (as in on the alert); 1803 as "a warning report." The verb is by 1864. Related: Alerted; alerting.

Related entries & more 
erectile (adj.)
1822, "pertaining to muscular erection," from French érectile, from Latin erect-, past participle stem of erigere "to raise or set up" (see erect (adj.)).
Related entries & more 
hump (v.)
"to bend or raise into a hump," 1840, from hump (n.). Meaning "do the sex act with" is attested from 1785, but the source indicates it is an older word. Related: Humped; humper; humping.
Related entries & more 

Page 3