Ucal in Fausset's Bible Dictionary

Agur spoke his words to Ithiel ("God with me"), and Ucal his disciples. (See ITHIEL.) From yakol "he was strong." Keil, guesses that Ithiel, "God with me," denotes those glorying in intimate communion with God, and a higher insight thereby. Ucal, "I am strong," denotes those boasting of their might and denying God; freethinkers fancying themselves above the revealed law and in atheism indulging the lusts of the flesh (Proverbs 30:1).