1. phrasal verbIf something doubles you up, or if you double up, you bend your body quickly or violently, for example because you are laughing a lot or because you are feeling a lot of pain.
...a savage blow in the crutch which doubled him up. [VERB noun PARTICLE]
They laugh so hard they double up with laughter. [VP + with/in]
Double over means the same as double up.
Everyone was doubled over in laughter. [VERB-ed PARTICLE]
2. See also double [sense 11]
More Synonyms of double up
See full dictionary entry for double