Wiktionary
alacritous
a. (context rare English) Brisk, speedy, with alacrity, quick and eager.
WordNet
alacritous
adj. quick and eager; "an alacritous response to the invitation"
Usage examples of "alacritous".
He wheeled, dodged between two Danes, end vanished down a game trail with alacritous churning of short legs.