ἁμιλλᾶσθαι
From LSJ
τὸ δ' ἐξαίφνης τὸ ἐν ἀναισθήτῳ χρόνῳ διὰ μικρότητα ἐκστάν → suddenly refers to what has departed from its former condition in a time imperceptible because of its smallness
Greek > English (Woodhouse Verbs Reversed)
(see also ἁμιλλάομαι): contend, hasten, argue with, compete with, contend with, discuss with, dispute with, emulate a person
Lexicon Thucydideum
certare inter se, aemulari, struggle with each other, to compete, 6.31.3.