c. 1300, conduyt, "conduct, guidance, an escorting party" (a sense now obsolete in this word but preserved in its doublet, conduct), from Old French conduit (12c.) "escort, protection; pipe, channel," from Latin conductus "a leading, a pipe," noun use of past participle of conducere "to lead or bring together; contribute, serve," from assimilated form of com "with, together" (see con-) + ducere "to lead" (from PIE root *deuk- "to lead").

Conduct and conduit differentiated in meaning from 15c. Conduit in the sense "medium or means of conveying" is from mid-14c.; as "pipe or tube or other channel for conveyance of water," late 14c.

1520s, "having the power or property of leading" (a sense now obsolete), from conduct (v.) + -ive. The sense in modern physics, "resulting from or pertaining to conduction," is from 1840. Related: Conductivity (1837).

1710, "bad management, neglect;" see mis- (1) "bad, wrong" + conduct (n.). Meaning "wrong conduct" is attested from 1729.

 "privilege of safe passage" granted by an authority, late 13c., from Old French sauf-conduit (13c.); see safe (adj.) + conduct (n.).

word-forming element meaning "together, with," sometimes merely intensive; it is the form of com- used in Latin before consonants except -b-, -p-, -l-, -m-, or -r-. In native English formations (such as costar), co- tends to be used where Latin would use con-.

Proto-Indo-European root meaning "to lead."

It might form all or part of: abduce; abducent; abduct; abduction; adduce; aqueduct; circumduction; conduce; conducive; conduct; conductor; conduit; deduce; deduction; dock (n.1) "ship's berth;" doge; douche; ducal; ducat; Duce; duchess; duchy; duct; ductile; duke (n.); educate; education; induce; induction; introduce; introduction; misconduct; produce; production; reduce; reduction; seduce; seduction; subduce; subduction; taut; team (n.); teem (v.1) "abound, swarm, be prolific;" tie (n.); tow (v.); traduce; transducer; tug; Zugzwang.

It might also be the source of: Latin dux (genitive ducis) "leader, commander," in Late Latin "governor of a province," ducere "to lead;" Old English togian "to pull, drag," teonteon "to pull, drag;" German Zaum "bridle," ziehen "to draw, pull, drag;" Middle Welsh dygaf "I draw."