Why is the ninth month called September?
1680s, from Late Latin catalepticus, from Greek kataleptikos, from kataleptos (see catalepsy). The noun meaning "one affected by catalepsy" is from 1851.
catalepsy cat·a·lep·sy (kāt'l-ěp'sē)
A condition that occurs in a variety of physical and psychological disorders and is characterized by lack of response to external stimuli and by muscular rigidity, so that the limbs remain in whatever position they are placed.