definiendum

noun

1. The term (word or phrase) defined in a definition (whether inside a sentence, as a dictionary entry, or otherwise).

   “However, most advocates of the importance of real definition have limited the definiendum to certain kinds of things: usually an abstract entity or a concept.”

   “The objects themselves are the definienda of the definition. The first set of properties through which the definienda are collected together to form a group is called ‘the limiting properties of being the definienda of the definition’.”