“Actualitas” is a Latin word invented in the medieval period to translate Aristotle’s energeia and entelecheia. Since “actus” is the past participle of “agere,” (to do, impel), originally actualitas was not a bad translation. “Actuality” has come to have something of a static connotation, and energeia is definitely dynamic, so “activity” would be a better translation. Aristotle lays out his theory of energeia in Metaphysics IX.6–9. [HDAGP]