late 14c., recusen, "to decline, refuse," especially "reject another's authority or jurisdiction over oneself as prejudiced," from Old French recuser (13c.) and directly from Latin recusare "make an objection against; decline, refuse, reject; be reluctant to," from re- (see re-) + causa (see cause (n.)). Specifically, in law, "reject or challenge (a judge or juror) as disqualified to act." The word now is used mostly reflectively. Related: Recused; recusing; recisative.

early 15c., "the dodging movements of a hunted animal" (a sense now obsolete); 1620s as "a trick, a stratagem, an artifice," from Old French ruse, reuse "diversion, switch in flight; trick, jest" (14c.), a noun from reuser "to dodge, repel, retreat; deceive, cheat," which is from Latin recusare "make an objection against; decline, refuse, reject; be reluctant to" (see recuse; also compare rush (v.)).

It also has been proposed that the French word may be from Latin rursus "backwards," or a Vulgar Latin form of refusare. Johnson calls it, "A French word neither elegant nor necessary."

The verb ruse was in Middle English (rusen), mid-14c. as "drive (someone) back in battle," also "retreat, give ground, withdraw;" late 14c., of game animals "travel so as to elude pursuit." The noun also was used in Middle English in the sense of "roundabout course taken by a hunter in pursuit of prey."

"a rapid or violent onset," 1831; see on + rush (n.).

also bullrush, popular name for tall rush-like plants growing in or near water (in Biblical use, the Egyptian papyrus), mid-15c., bolroysche, from rush (n.1); the signification of bull is doubtful.

"a light made from a stripped, dried rush dipped repeatedly in tallow," 1710, from rush (n.1) + light (n.). Earlier rush-candle (1590s). Figurative of something insignificant, thin, or faintly glimmering.