h₁rewǵ-
“to vomit, to belch”belch, smoke, reek
Root for smoking/reeking, yielding English reek, Lithuanian rugti, Latin ructare (to belch).
Discussion
The PIE root *h₁reǵ- (to move in a straight line, to stretch, to direct, to rule) is one of the most politically and geometrically productive roots in the reconstructed vocabulary — a single concept of straightness that generated the Western vocabulary of kingship, correctness, law, and spatial orientation.
Latin rēx (king, ruler — genitive rēgis) continues the root in its most prestigious form: the king as "the one who directs, who keeps things straight." From rēx and the verb regere (to guide, to rule, to keep straight) English inherits: regal, regent, regime, regiment, region (a directed territory), regulate, reign, and the vast family built on rectus (made straight, correct) — rector, rectify, correct (con-rectus, straightened together), erect (ē-rectus, straightened up), direct (dī-rectus, straightened apart), and rectangle (rectus + angulus, a straight-angled figure).
The English word right descends from Old English riht, from PGmc *rehtaz, from the same PIE root — making right a native English cognate of Latin rēx. The conceptual equation is fundamental: what is right is what is straight; what is straight is what is correct; what is correct is what is ruled. The political sense (rights, as in legal entitlements) and the directional sense (right, as opposed to left) both derive from this equation of straightness with propriety.
Sanskrit rā́jan- (king, ruler) and the related rāj- (to rule) continue the root in Indo-Iranian. The title Maharaja (mahā-rāja, "great king") and the word raj (as in British Raj) are direct descendants. The Celtic reflex appears in the Gaulish personal name -rīx (Vercingetorix, "great king of warriors") and Old Irish rí (king).
Greek oregein (ὀρέγειν, "to stretch, to reach out") preserves the physical "stretching" sense without the political extension — a reminder that the kingship metaphor was not inevitable but a specific cultural development in the western branches.
The root's journey from "to go straight" to "to rule" to "to be correct" encodes a political philosophy in its etymology: legitimate authority IS straightness, proper rule IS the maintenance of a straight line. When English speakers say "that's right" they are, without knowing it, invoking a PIE concept of cosmic straightness that also named their kings.
Notes
Pokorny 871. English reek from Germanic *reukan-.