Oligodactyly

Oligodactyly (from the Ancient Greek oligos meaning "few" and δάκτυλος daktylos meaning "finger") is the presence of fewer than five fingers or toes on a hand or foot.

It is quite often incorrectly called hypodactyly, but the Greek prefixes hypo- and hyper- are used for continuous scales (e.g. in hypoglycaemia and hypercholesterolemia). This as opposed to discrete or countable scales, where oligo- and poly- should be used (e.g. in oligarchy and polygamy). Oligodactyly is therefore the opposite of polydactyly. Very rare, this medical condition usually has a genetic or familial etiology.