*pʷu

This is one of over 30 TB etyma showing interchange between *p- and *w-, including such important roots as AXE, BAMBOO, BELLY, MAN/HUSBAND, PIG, etc. In this volume, see also #674 PTB *pʷam WOMB / PLACENTA / BELLY / STOMACH / NEST. These are reconstructed with *pw- clusters in the revised version of STC (e.g. *pak = *pwak; see n. 78, pp. 23-4). I originally preferred to treat the stop component as prefixal (e.g. *p-wak), but later abandoned this approach in favor of an “extrusional” interpretation, where the [-w-] is considered to be a mere phonetic perseveration of the preceding stop, e.g. *pʷak (see Matisoff 2000a). This extrusion is especially common before the vowel [-a-], but also, as in EGG, occasionally occurs before [-u-]. See also HPTB:61-62.

In the following sections, the reflexes of this etymon are presented separately, according to whether they derive from the variant with semivowel (*wu) or stop (*pu) initial.