recto (n.)

"opposite of left," early 12c., riht, from Old English riht, which did not have this sense but meant "good, proper, fitting, straight" (see right (adj.1)). It is a specialized development of the adjective that apparently began in late Old English on the notion of the right hand as normally the stronger of the two, or perhaps the "correct," hand. By c. 1200 this was extended to that side of the body, then to its limbs, clothing, etc., and then transferred to other objects.

The usual Old English word for the opposite of left was swiþra, literally "stronger." "The history of words for 'right' and 'left' shows that they were used primarily with reference to the hands" [Buck]. Similar sense evolution in Dutch recht, German recht "right (not left)," from Old High German reht, which meant only "straight, just." Compare Latin rectus "straight; right," also from the same PIE root.

The usual PIE root (*deks-) is represented by Latin dexter. Some other "right-not-left" words derived in a similar pattern are French droit, from Latin directus "straight;" Lithuanian labas, literally "good;" and Slavic words (Bohemian pravy, Polish prawy, Russian pravyj) from Old Church Slavonic pravu, literally "straight" (from PIE *pro-, from root *per- (1) "forward," hence "in front of, before, first, chief").

The political sense of "conservative" is recorded by 1794 (adj.), 1825 (n.), a translation of French Droit "the Right, Conservative Party" in the French National Assembly (1789; see left (adj.)).

Proto-Indo-European root meaning "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule."

It forms all or part of: abrogate; address; adroit; Alaric; alert; anorectic; anorexia; arrogant; arrogate; bishopric; correct; corvee; derecho; derogate; derogatory; Dietrich; direct; dress; eldritch; erect; ergo; Eric; Frederick; Henry; incorrigible; interregnum; interrogate; maharajah; Maratha; prerogative; prorogue; rack (n.1) "frame with bars;" rail (n.1) "horizontal bar passing from one post or support to another;" Raj; rajah; rake (n.1) "toothed tool for drawing or scraping things together;" rake (n.2) "debauchee; idle, dissolute person;" rakish; rank (adj.) "corrupt, loathsome, foul;" real (n.) "small Spanish silver coin;" realm; reck; reckless; reckon; rectangle; rectify; rectilinear; rectitude; recto; recto-; rector; rectum; regal; regent; regicide; regime; regimen; regiment; region; regular; regulate; Regulus; Reich; reign; resurgent; rex; rich; right; Risorgimento; rogation; royal; rule; sord; source; subrogate; subrogation; surge; surrogate; viceroy.

It is the hypothetical source of/evidence for its existence is provided by:

Sanskrit raj- "a king, a leader," rjyati "he stretches himself," riag "torture" (by racking); Avestan razeyeiti "directs," raštva- "directed, arranged, straight;" Persian rahst "right, correct;" Latin regere "to rule, direct, lead, govern," rex (genitive regis) "king," rectus "right, correct;" Greek oregein "to reach, extend;" Old Irish ri, Gaelic righ "a king," Gaulish -rix "a king" (in personal names, such as Vircingetorix), Old Irish rigim "to stretch out;" Gothic reiks "a leader," raihts "straight, right;" Lithuanian raižytis "to stretch oneself;" Old English rice "kingdom," -ric "king," rice "rich, powerful," riht "correct;" Gothic raihts, Old High German recht, Old Swedish reht, Old Norse rettr "correct."