change up verb 4/ˈtʃeɪndʒʌp/ noun 2forms 4 verb4 •(informal) To vary.change it up •To change to a higher gear in a vehicle. •To throw a pitch at a much slower than expected speed.He changed up on Wilson after three fastballs and struck him out. •To confuse someone by doing something unexpected or in an unexpected way.I thought that we were going to study the project some more, but then he came back from the weekend and changed up, making it a top priority. change-up /ˈtʃeɪndʒʌp/ noun2 •A pitch thrown with the arm motion of a fastball, but which travels at a much slower velocity because it is released without the fingers adding power to the delivery.The pitcher had a devastating change-up. •An unexpected event.This RFQ is a real change-up. formschanged up · changing up · changes up · change-ups