rider n.

Middle English riden, from Old English ridan "sit or be carried on" (as on horseback), "move forward; rock; float, sail" (class I strong verb; past tense rad, past participle riden), from Proto-Germanic *ridan (source also of Old Norse riða, Old Saxon ridan, Old Frisian rida "to ride," Middle Dutch riden, Dutch rijden, Old High German ritan, German reiten), from PIE *reidh- "to ride" (source also of Old Irish riadaim "I travel," Old Gaulish reda "chariot"). Common to Celtic and Germanic, perhaps a loan word from one to the other.

Of a ship, "to sail, float, rock," c. 1300. The meaning "heckle" is by 1912 from earlier sense of "dominate cruelly, have the mastery of, harass at will" (1580s) on the notion of "control and manage," as a rider does a horse, especially harshly or arrogantly. The verb in venery is from mid-13c.

To ride out "endure (a storm, etc.) without great damage" is from 1520s, literal and figurative. To let (something) ride "allow to pass without comment or intervention" is by 1921. To ride herd on "guard and control" is by 1897, from cattle-driving. To ride shotgun "ride in the passenger seat of an automobile" is by 1919, from the custom of having an armed man up beside the driver of a stagecoach to ward off trouble. To ride shank's mare "walk" is from 1846 (see shank (n.)). The ____ rides again cliche is from Hollywood movie titles ("Destry Rides Again," 1939).

mid-14c., "one who rides out or forth," especially a royal officer charged with collecting taxes, from out- + rider. The verb outride is from c. 1200 as "to ride forth, ride out" (utridan), from 1520s as "pass in riding, ride faster than." Related: Outrode; outridden.