Definition - The branch of grammar that studies the formation and structure of words, i.e. it is the study of how morphemes work.

1. As opposed to syntax, which is the study of the arrangement of groups of words such as phrases, clauses, and sentences.
2. There are two types: inflectional morphology, the study of inflections, and lexical morphology, the study of word formation.

Etymology -
The word derives from the Greek morphe, form or shape + ology, study of.

Oxford English Dictionary -
Its first citation in this sense is from 1869:
"By the morphology of a language we mean the general laws of its grammatical structure."
(Farrar Fam. Speech iv. 118)

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