up
to contract the muscles of your eyes or face because the light is too strong, you are in pain, etc. :
He took a sip of the medicine and screwed up his face.
up
to contract the muscles of your eyes or face because the light is too strong, you are in pain, etc. :
He took a sip of the medicine and screwed up his face.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005