πιών

From LSJ

ἔνδον σκάπτε, ἔνδονπηγή τοῦ ἀγαθοῦ καί ἀεί ἀναβλύειν δυναμένη, ἐάν ἀεί σκάπτῃς → Dig within. Within is the wellspring of Good; and it is always ready to bubble up, if you just dig. | Look within. Within is the fountain of the good, and it will ever bubble up, if thou wilt ever dig.

Source

French (Bailly abrégé)

οῦσα, όν :
part. ao.2 de πίνω.

Russian (Dvoretsky)

πιών: οῦσα, όν part. aor. 2 к πίνω.

Dutch (Woordenboekgrieks.nl)

πιών -οῦσα -όν ptc. aor. act. van πίνω.