Cladistics
Merriam-Webster on cladistics
Google indexed this page today from the online version of Merriam-Webster dictionary:
Main Entry: cla·dis·tics
Pronunciation: \kl?-?dis-tiks, kla-\
Function: noun plural but singular in construction
Date: 1965: a system of biological taxonomy that defines taxa uniquely by shared characteristics not found in ancestral groups and uses inferred evolutionary relationships to arrange taxa in a branching hierarchy such that all members of a given taxon have the same ancestors
— cla·dist \?kla-dist, ?kl?-\ noun
— cla·dis·tic \kl?-?dis-tik, kla-\ adjective
— cla·dis·ti·cal·ly \-ti-k(?-)l?\ adverb
I don’t know when was this entry actually added to the dictionary, but it is nicely defined.