Definition: (from dictionary.com)
1. informal. a fit of hysterical excitement or anger
"My boss had a conniption when I overslept and was late for work."
"She broke her nail and had a conniption. I dumped her."
Origin: (from etymonline.com)
"1833, American English, origin uncertain; perhaps related to corruption, which was used in a sense of 'anger' from 1799, or from English dialectal canapshus 'ill-tempered, captious,' probably a corruption of captious."