Lewis Short
(adjective) : in-festīvus, a, um
* Not agreeable, not pleasant, inelegant (post-class.): subagresti ingenio et infestivo,Gell. 1, 5, 3.— Adv.: infestīvĭter, inelegantly: cetera vertit non infestiviter,i. e. quite elegantly,Gell. 9, 9, 9.
Charlton T. Lewis, Charles Short, A Latin Dictionary