Grammatical morphology refers to the structure of words that results from combining word roots with endings that mark grammatical relations, such as the -s at the end of verbs to mark agreement with a third-person subject, as in she works" or the -ed at the end of verbs to mark the past tense (she worked). Grammatical morphology is also known as Inflectional morphology.
Lexicon of Psychology - Terms, Treatments, Biographies,