"morally correct," Old English riht "just, good, fair; proper, fitting; straight, not bent, direct, erect," from Proto-Germanic *rekhtaz (cf. Old Frisian riucht "right," Old Saxon reht, Middle Dutch and Dutch recht, Old High German reht, German recht, Old Norse rettr, Gothic raihts), from PIE root *reg- "move in a straight line," also "to rule, to lead straight, to put right" (see regal; cf. Greek orektos "stretched out, upright;" Latin rectus "straight, right;" Old Persian rasta- "straight, right," aršta- "rectitude;" Old Irish recht "law;" Welsh rhaith, Breton reiz "just, righteous, wise").
Cf. slang straight (adj.1) "honest, morally upright," and Latin rectus "right," literally "straight," Lithuanian teisus "right, true," literally "straight." Greek dikaios "just" (in the moral and legal sense) is from dike "custom." As an emphatic, meaning "you are right," it is recorded from 1580s; use as a question meaning "am I not right?" is from 1961. The sense in right whale is "justly entitled to the name." Right stuff "best human ingredients" is from 1848, popularized by Tom Wolfe's 1979 book about the first astronauts. Right of way is attested from 1767. Right angle is from late 14c.
