#6723 PTB *d-(p/b)u-k BELLY / STOMACH / CAVE

This root has many allofams, displaying variation in prefix, voicing or leniting of the initial, alternation between the high vowels ‑u‑ and ‑i‑, and presence or absence of final stop. The reflexes also display considerable variation in meaning, ranging from the body part ‘stomach’ to other vital organs like ‘heart’ to hollow natural objects like ‘cave’.

See the extended discussion in Matisoff 1978b:124-126 (VSTB).