Which of the following best defines morphology?

Morphology is best defined as the study of the structure of words. This field examines how words are formed, including the analysis of their internal structure and the rules that govern word formation. Morphologists look at morphemes, which are the smallest units of meaning or grammatical function within a word. For example, the word "unhappiness" consists of three morphemes: "un-", "happy", and "-ness," each contributing to the overall meaning of the word.

This definition highlights the primary focus of morphology, which distinguishes it from other linguistic domains. Phonetics, for example, concentrates on the sounds of language, while semantics deals with meaning. Additionally, grammar encompasses broader aspects of language structure and usage beyond just the word level, including sentence structure and syntax. Therefore, the option that emphasizes the structure specifically related to words accurately captures the essence of morphology.