Most probably, from banû
‘to build’ (AHw), even if the derivational pattern is unclear (Kraus 1935, 46, GAG § 57b Anm.). This etymology is particularly appealing in view of the fact that Punnānū can also mean ‘creature’ (Lambert 1998, 153). A derivation from banû
‘to be beautiful’ (CAD) seems to be based on the assumption that Punnānū is related to būnu ‘face’ which, in turn, is commonly derived from banû
‘to be beautiful’.