krew-
“to be raw, bloody flesh”Source of Latin crūdus, English raw, cruel, crude
Root for raw flesh and blood, yielding Latin crūdus, cruor and English raw, cruel, crude.
Discussion
The PIE root *krew- (to be raw, to consist of bloody flesh) is the base from which *krewh₂- (raw flesh, blood — see the full treatment at id 58) was extended. The root produced the vocabulary of raw material, cruelty, and visceral substance.
Latin crūdus (raw, bloody, undigested) gave English crude (unrefined, in its raw state), cruel (crūdēlis, "raw, bloody" → merciless — cruelty as the quality of being bloody/unrefined), and the combining form crudo- in culinary vocabulary. Latin cruor (gore, flowing blood) connects directly.
English raw (OE hrēaw, from PGmc *hrawaz) descends from the same root with Grimm's Law: PIE *k > PGmc *h (later lost). Raw is thus a native English cognate of crude — both meaning "in the natural, unprocessed state."
Greek kréas (κρέας, "flesh, meat") gave English pancreas ("all-flesh," the organ named for its fleshy consistency) and the combining form creo-/kreas- in medical terminology.
Sanskrit kravís- (raw flesh, carrion) preserves the Indo-Iranian reflex in sacrificial and martial contexts.
The root's semantic core is the state BEFORE processing — before cooking, before refining, before civilisation. Raw, crude, and cruel all name the condition of things in their natural, unimproved state. The PIE speakers who named this condition generated a vocabulary that their descendants would use for both material science (crude oil) and moral philosophy (cruel punishment).