ἀντιδιδόναι

From LSJ

ταῦτα δηλώσω αὐτός τε νοσήσας καὶ αὐτὸς ἰδὼν ἄλλους πάσχοντας → I shall describe those symptoms, since I myself had the disease and witnessed as well what others were suffering

Source

Greek > English (Woodhouse Verbs Reversed)

(see also ἀντιδίδωμι): give in exchange, give in return, give instead, pay back

Lexicon Thucydideum

referre, rependere, to return, repay, 3.63.4,
PASS. 1.41.1, 3.40.3,
poenas vicissim dare, to inflict punishment in turn, 2.53.4,
idem, the same 3.66.3.