Definition of "slip up" []

• To err, falter; to make a mistake. (verb)

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• "We'd been so intent on Von Schuler, we hadn't noticed Rick slip up behind us."
• "The Piute Indians make use of a bandage in a somewhat different way; they clasp a leather girdle around the waist above the fundus of the womb, not so tight-fitting but that it will slip up and down on the body; then, as the expulsive pains come on, three, four, or more women push the girdle down after the escaping child."
• "The Juggler will eventually slip up and drop the ball."