morphology

In linguistics, morphology is the study of how words are formed, and how they relate to one another within a language. Most approaches to morphology investigate the structure of words in terms of morphemes, which are the smallest units in a language with some independent meaning or grammatical function. Morphemes include roots that can exist as words by themselves, but also categories such as affixes that can only appear as part of a larger word. For example, in English the root catch and the suffix ‑ing are both morphemes; catch may appear on its own as a word, or it may be combined with ‑ing to form the new word catching. Morphology also analyzes how words behave as parts of speech, and how they may be inflected to express grammatical categories such as number, tense, and aspect. Morphology also concerns productivity, or how speakers create words in specific contexts. These processes evolve over the history of a language.

The basic fields of linguistics broadly focus on language structure at different "scales". Morphology is considered to operate at a larger scale than phonology, which investigates the categories of speech sounds that are distinguished within a spoken language, and thus may constitute the difference between a morpheme and another; and at a smaller scale than syntax, which investigates how words form phrases and sentences. Morphological typology is a distinct field that categorises languages based on the morphological features they exhibit.