They were believed to have 1000 feet, hence milli- (which nowadays means one-thousandth) and -pede (Latin for foot). Upon closer inspection they were found to have merely a hundred or so.
The name "millipede" is derived from the Latin mille, for "thousand" and ped (inflected form of pes) for "foot." Millipedes do not actually have a thousand feet, but can have several hundred,...