usefully
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 > Greek (Woodhouse)
adverb
P. and V. προὔργου, P. συμφόρως, χρησίμως, ὠφελίμως, συμφερόντως, λυσιτελούντως, εὐχρήστως, χρηστικῶς, ἐπιτηδείως.
