early 15c., "to guide, accompany and show the way," from Latin conductus, 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").
Sense of "to lead, command, direct, manage" is from mid-15c., originally military. General meaning "to direct, manage, act as leader of" is from 1630s; especially of a musical performance (1791).
Meaning "behave in a certain way" is from 1710. In physics, "to carry, convey, transmit," 1740. Related: Conducted; conducting. An earlier verb in the same sense was condyten (c. 1400), which goes with conduit.