mess up verb 8/ˈmɛsˌʌp/ noun 2forms 4 verb8 •To make a mess of; to untidy, disorder, soil, or muss.The afternoon breeze messed up my hair. •To botch, bungle; to perform poorly on.Well, I messed up my solo, but otherwise it was a good concert. •To make a mistake; to do something incorrectly; to perform poorly.He has a hard time getting started because he's afraid he'll mess up.She messed up on her final exam. •To cause a problem with; to introduce an error or mistake in; to make muddled or confused; spoil; ruin.The change messed something up, and it's not working anymore. •To damage; injure.He messed up his elbow at the track meet. •(slang) To manhandle; beat up; rough up.Her brother's friends messed him up a little after he cheated on her. •(slang) To discombobulate, utterly confuse, or confound psychologically; to throw into a state of mental disarray.That girl totally messed me up, man. I'm not sure who I am anymore. •To cause (another person) to make unwanted mistakes in a given task, usually through distraction or obnoxious behavior.Stop bumping me! You keep messing me up! mess-up /ˈmɛsˌʌp/ noun2 •(informal) A mistake or fiasco; something that has gone wrong. •(informal) A person who makes many mistakes. formsmessed up · messing up · messes up · mess-ups