Antonyms for the phrase "hold up one's end" could be "drop the ball," "give up," or "abandon." Dropping the ball refers to failing to meet one's responsibilities or not completing a task. Giving up is surrendering to a challenge or abandoning a commitment. Abandoning means to leave something behind or to give up on it. It is essential to note that none of these antonyms are positive behaviors or attitudes. Holding up one's end implies responsibility, commitment, and dependability, while dropping the ball, giving up, or abandoning reflects laziness, negligence, or irresponsibility. Therefore, it is best to strive for the positive behavior of holding up your end by meeting your obligations and following through on commitments.
