"Owns up" is an idiomatic phrase that means to admit or confess to something, especially a mistake or wrongdoing. Some synonyms for "owns up" include "acknowledge," "admit," "confess," "take responsibility," "come clean," and "fess up." These synonyms all imply a willingness to be honest and accountable for one's actions, even when it may be difficult or uncomfortable. Using these synonyms instead of the phrase "owns up" can add variety and nuance to one's language. It's important to remember that owning up to one's mistakes is a sign of integrity and is necessary for personal growth and learning.