ἀπεῖναι

From LSJ

ἀσκεῖν περὶ τὰ νοσήματα δύο, ὠφελεῖν ἢ μὴ βλάπτειν → strive, with regard to diseases, for two things — to do good, or to do no harm | as to diseases, make a habit of two things — to help, or at least, to do no harm

Source

Greek > English (Woodhouse Verbs Reversed)

(see also ἄπειμι): be absent, be away, be distant, be far

Lexicon Thucydideum

abesse, to be absent, 1.105.4, 1.141.4, 3.13.5, 5.44.1. 6.13.1,
remotorum, distant, 6.24.3, 6.29.2, 6.13.2. 8.87.1.
deesse, to be lacking, 2.61.2.