εφτάχρονος

From LSJ

ἐν πίθῳ τὴν κεραμείαν μανθάνειν → in breaking many pots, the potter learns his craft | of those who undertake the most difficult tasks without learning the elements of the art | don't run before you can walk

Source

Greek Monolingual

-η, -ο (ΑΜ ἑπτάχρονος, -ον)
νεοελλ.
επταετής
αρχ.-μσν.
με επτά βραχείς χρόνους στην προσωδία.