1) Inflectional morphology 2) Morphology 3) The inflections so studied 
grammar book; science of inflections in grammar
• (n.) The accidents, of inflections of words; the rudiments of grammar. • (n.) The rudiments of any subject.
Ac'ci·dence noun [ A corruption of Eng. accidents , plural of accident . See Accident , 2.] 1. The accidents, of inflections of words; the rudiments of grammar. Milton. 2. The rudiments of any subject. Lowell. 
the rudiments or essentials of a subject. · · the study of inflection as a grammatical device. · the inflections so studied.