1620s, from Medieval Latin tendentia "inclination, leaning," from Latin tendens, present participle of tendere "to stretch, extend, aim" (from PIE root *ten- "to stretch"). Earlier in same sense was tendaunce (mid-15c.), from Old French tendance.
early 15c., impetous "rapid movement, rush;" 1640s, with modern spelling, "force with which a body moves, driving force," from Latin impetus "an attack, assault; rapid motion; an impulse; violence, vigor, force;" figuratively "ardor, passion," from impetere "to attack," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + petere "aim for, rush at" (from PIE root *pet- "to rush, to fly").
"to incline, to move in a certain direction," early 14c., from Old French tendre "stretch out, hold forth, hand over, offer" (11c.), from Latin tendere "to stretch, extend, make tense; aim, direct; direct oneself, hold a course" (from PIE root *ten- "to stretch"). The PIE root produced two Latin verbs, tendere "to stretch" and tenere "to hold, grasp" (source of tenacity, etc.), perhaps from inflected forms in the one PIE verb. Both Latin verbs have past participle tentus.
early 13c., redien, "to administer" (a sense now obsolete); c. 1300, "to take aim;" mid-14c., "to make (something) ready, prepare, put into proper condition or order," from ready (adj.). "Somewhat rare between the 15th and 19th c." [OED]. Related: Readied; readying. Compare Dutch reeden "prepare, dress; German bereiten, Danish berede "prepare, get ready;" also compare redd (v.).