'Right' is PIE *reg- (to move straight) — the root of 'regal,' 'regime,' 'regulate,' and 'rectify.'
On or toward the side of the body opposite the heart in most people; also, morally correct, just, or proper.
From Old English 'riht' (straight, just, proper, right-hand), from Proto-Germanic *rehtaz, from the PIE root *h₃reǵ- meaning 'to straighten, to direct, to rule.' The same root produced Latin 'rēctus' (straight, right), 'rēx' (king), and 'regere' (to rule), as well as Sanskrit 'ṛjú' (straight). The merging of 'morally correct' and
The PIE root *h₃reǵ- that gave English 'right' also produced Latin 'rēx' (king), 'regere' (to rule), 'rēgula' (rule, straight stick), and through these: 'regal,' 'regent,' 'regime,' 'regulate,' 'rectangle,' and 'rectify.' The idea of 'straightness' branched into moral correctness, political authority, and geometric precision — all from the same ancient word.