1. A form of epilepsy with very brief, unannounced lapses in consciousness: A petit mal is a seizure that involves a short loss of awareness, which can be accompanied by blinking or mouth twitching.

A seizure of a petit mal also takes the form of a staring spell; as if the person suddenly seems to be "absent" or "not aware" of what is going on!

2. Etymology: from French, "little illness" from petit, "small" + mal, "illness"; as, in seizures which are also known as "absence seizures".