late 14c., mocioun, "process of moving; change of place, continuous variation of position;" also "suggestion, proposal or proposition formally made," from Old French mocion "movement, motion; change, alteration" (13c., Modern French motion) and directly from Latin motionem (nominative motio) "a moving, a motion; an emotion," from past-participle stem of movere "to move" (from PIE root *meue- "to push away").
From c. 1400 in legal sense of "application to a court or judge." To be in motion "in a state of motion" is from c. 1600; to set in motion "set working" is from 1590s. To go through the motions in the figurative sense of "pretend, do in a perfunctory manner" is by 1816 from the notion of "simulate the motions of." Motion picture is attested from 1896; motion sickness by 1942.
Rev. G.S. White said : The Presbytery does not favour the proposition of the Richmond Convention, and thinks the appointment of the Committee unnecessary; yet I suppose, that like the man who had nothing to eat, yet always spread the table, and sat down, and went through the motions—so we, according to our brother, are in honour bound, to appoint the Committee and go through the motions!—[Laughter] [The Presbyterian Magazine, May, 1858]
late 15c., "to request, petition" (obsolete), from motion (n.). The sense in parliamentary procedure, "to propose, move" is by 1747; with meaning "to guide or direct by a significant sign, gesture, or movement," as with the hand or head, it is attested from 1787. Related: Motioned; motioning.
medical word-forming element meaning "slow, delayed, tardy," from Greek bradys "slow;" as in bradycardia (1890), with Latinized form of Greek kardia "heart;" bradykinesia, "slow movement," with Greek kinēsis "movement, motion;" bradypnea, with Greek pneo/pnein "to breathe."
1777, "a projecting part of a rotating machinery used to impart motion to another part," from Dutch cam "cog of a wheel," originally "comb," from Proto-Germanic *kambaz "comb," from PIE root *gembh- "tooth, nail." It is thus a cognate of English comb (n.). This might have combined with English camber "having a slight arch;" or the whole thing could be from camber. It converts regular rotary motion into irregular, fast-and-slow rotary or reciprocal motion. "The original method was by cogs or teeth fixed or cut at certain points in the circumference or disc of a wheel ..." [OED]. Cam-shaft attested from 1850.
in music, "becoming gradually slower," 1811, from Italian, present participle of ritardare "to slow down," from Latin retardare "to make slow" (see retardation). The Italian plural is ritardandi.