τρίναξ
From LSJ
κάλλιστον ἐφόδιον τῷ γήρᾳ ἡ παιδεία (Aristotle, quoted by Diogenes Laertius 5.21) → the finest provision for old age is education
English (LSJ)
ᾰκος, ἡ, (ἀκή (A))
A like θρῖναξ, three-pronged mattock, AP6.104 (Phil.) [where ι is short].
German (Pape)
[Seite 1144] ακος, ἡ, der Dreizack, Philp. 14 (VI, 104), ξυλίνας.