Piau (i), n. 1. Axe; generally restricted to an iron axe. Kia whakarikaia te piau tawhiti (M. 85).
2. Iron. (mod.)
pīauau, n. 1. Knife, cutting instrument. = mira.
2. Iron. Ka hewa te kai reka i tukua atu ai hei hoko piauau (M. 372, MS.).
Williams Dictionary
Pīau (ii) pīauau, a. Suppurating, offensive. Te piauautanga o te moko (The matter from a sore tattoo mark).
Williams Dictionary