The phrase "be usual" means to be typical or standard. Antonyms of this phrase include "be uncommon" or "be unusual," which means to be out of the ordinary or not typical. Other antonyms for "be usual" are "be atypical," "be exceptional," or "be rare." These antonyms describe situations or objects that deviate from the norm, such as rare artifacts, unique phenomena, or extraordinary occurrences. Using antonyms of "be usual" can add variety and interest to your speech or writing, conveying the idea of something unique or unexpected.