Which term describes a morpheme that occurs before or after a base?

The term that describes a morpheme occurring before or after a base is "Affix." Affixes are morphemes that attach to a base or root word to modify its meaning or create a new word. There are two main types of affixes: prefixes, which come before the base, and suffixes, which come after it. For example, in the word "unhappiness," "un-" is a prefix that modifies the base "happy," and "-ness" is a suffix that changes the word into a noun.

Understanding the role of affixes in word formation is essential as it helps educators teach students how to decode and understand complex words, enhancing their vocabulary and literacy skills. This knowledge is foundational in early reading development and language acquisition.