(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.) Thetic is from Greek thetikós, equivalent to thet(ós) placed, poly is from Greek polýs meaning "many" the word polythetic thus refers to "many in a place/category"
- (of a class of things) Having many, but not all properties in common.
- A polythetic taxon is one where the constituent organisms share a large number of characteristics.