An important aspect of grammar, but far less so than syntax. Morphology is the study of the way words are formed from smaller units called morphemes. A morpheme is the smallest part of a word that can create or change the word's meaning or function (e.g. un-, happy, -ness). Prefixes and suffixes (i.e. affixes such as, e.g. un-, -tion) are called bound morphemes because they cannot exist without being bound to a base or root word base words (e.g. interest, intent) are called free morphemes because they can exist as independent root words.

» Linguistic Library (Mike Green)