Etymology
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instructor (n.)

mid-15c., from Old French instructeur (14c.) and directly from Medieval Latin instructor "teacher" (in classical Latin, "preparer"), agent noun from instruere "arrange; inform, teach" (see instruct).

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drill (n.1)

"tool for making holes in hard substances," 1610s, from Dutch dril, drille "a hole, instrument for boring holes," from drillen "to bore (a hole), turn around, whirl," from PIE root *tere- (1) "to rub, turn."

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drill (n.2)

"small furrow; trench or channel in which seeds are deposited," 1727; also "machine for sowing seeds" (1731), from obsolete drill "rill, trickling stream" (1640s), which is of unknown origin; perhaps connected to drill (n.1).

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drill (n.4)

"West African baboon species," 1640s, perhaps from a native word (compare mandrill).

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drill (n.3)

also drilling, kind of coarse, stout twilled cloth, 1743, from French drill, from German drillich "heavy, coarse cotton or linen fabric," from Old High German adjective drilich "threefold," from Latin trilix (genitive trilicis) "having three threads, triple-twilled," from tri- (see tri-) + licium "thread," a word of unknown etymology. So called in reference to the method of weaving it.

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drill (v.1)

"pierce or make a hole in with a drill or similar tool," c. 1600 (implied in drilling), from Dutch drillen "to bore (a hole), turn around, whirl," from Proto-Germanic *thr- (source also of Middle High German drillen "to turn, round off, bore," Old English þyrel "hole"), from PIE root *tere- (1) "to rub, turn," with derivatives referring to twisting, boring, and drilling. Related: Drilled, drilling. Compare thrill, the native English form of the word. Drill-press "drilling machine for boring holes in metal" is by 1850.

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drill (v.2)

"to instruct in military exercise," 1620s (a sense also found in Dutch drillen and the Danish and German cognates), probably from drill (v.1) on the notion of troops "turning" in maneuvers. Related: Drilled, drilling.

As a noun, "act of training soldiers in military tactics," 1630s; the extended sense of "the agreed-upon procedure" is by 1940. Drill-sergeant "non-commissioned officer who instructs soldiers in their duties and trains them in military movements" is by 1760. Drill-master "one who gives practical instructions in military tactics" is by 1766.

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fire-drill (n.)

1865, originally a device for making fire by the twirled stick method, from fire (n.) + drill (n.1). Meaning "rehearsal of what to do in a fire" is from 1884 (originally it also involved fighting the fire), from drill (n.) in the "agreed-upon procedure" sense (see drill (v.)).

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preceptor (n.)

early 15c., preceptour, "tutor, instructor, teacher" (the earliest reference might be to "expert in the art of prose composition"), from Latin praeceptor "teacher, instructor," agent noun from praecipere (see precept). Medical sense of "physician who gives students practical training" is attested by 1803. Related: Preceptorial.

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catechectic (adj.)

"consisting of questions and answers," 1660s, from Latinized form of Greek katēkhetikos, from katekhetēs "an instructor," from katēkhizein "teach orally, instruct by word of mouth," from katēkhein "to resound" (see catechesis). Related: Catechectical(1610s). 

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