διασφάλλω
From LSJ
Ζῆν οὐκ ἄξιος, ὅτῳ μηδὲ εἷς ἐστι χρηστὸς φίλος → Life is not worth living if you do not have at least one friend.
English (LSJ)
A overturn utterly, τὴν τέχνην Luc.Abd.17:—Pass., to fail of, be disappointed of, τινός Aeschin.2.35,3.91, D.S.20.10; τῇ προνοία, ἐν πράξεσι, Plb.5.81.7,4.14.3, cf. Arist.Ath.19.3; πάντα δ. Vett.Val.116.34.