ἀντίπετρος
From LSJ
πολλάκις δοκεῖ τὸ φυλάξαι τἀγαθὰ τοῦ κτήσασθαι χαλεπώτερον εἶναι → it often proves harder to keep than to win prosperity | it is often harder for men to keep the good they have, than it was to obtain it
English (LSJ)
ον,
A like stone, rocky, S.OC192 codd. (lyr.). II in Theoc.Syrinx 2 (acc. to Sch.), exchanged for a stone, of Zeus in his infancy.