Antonyms are words that are opposite in meaning to each other. The word "opportunenesses" refers to the quality of being timely or suitable, so antonyms for this word would be the opposite of that. Some possible antonyms for "opportunenesses" could include words like "inappropriateness," "untimeliness," "infelicity," "unsuitability," or "impropriety." These words describe situations or actions that are poorly timed, misplaced or not well-suited to the circumstances, embarrassing, or unacceptable. In sum, antonyms for "opportunenesses" typically describe situations or actions that are not adapted to the proper time, place, or occasion.