Wiktionary
semanticity
n. 1 The quality of a linguistic system has being able to convey meanings 2 The condition of being semantic
Wikipedia
Semanticity
Semanticity is one of Charles Hockett's 16 design features of language. Semanticity refers to the use of arbitrary or nonarbitrary signals to transmit meaningful messages.
Semantics is the meaning of words. Therefore, semanticity is its noun form.