εὐχερές
From LSJ
Τὸ νικᾶν αὐτὸν αὑτὸν πασῶν νικῶν πρώτη τε καὶ ἀρίστη. Τὸ δὲ ἡττᾶσθαι αὐτὸν ὑφ' ἑαυτοῦ πάντων αἴσχιστόν τε ἅμα καὶ κάκιστον. → Τo conquer yourself is the first and best victory of all, while to be conquered by yourself is of all the most shameful as well as evil
Russian (Dvoretsky)
εὐχερές: τό небрежность, легкомыслие: τὸ εὐ. τῶν ὀνομάτων Plat. небрежное (неточное) словоупотребление; ἐν εὐχερεῖ θεῖναί τι Soph. пренебречь чем-л.