General terms:
* Morphemes: This is the most general term for the smallest meaningful unit of a language. Morphemes can be individual words or parts of words.
* Word elements: This is a broader term that encompasses all the different parts of a word, including morphemes, prefixes, suffixes, and root words.
Specific terms:
* Prefix: A word part that comes at the beginning of a word (e.g., "un-" in "unhappy").
* Suffix: A word part that comes at the end of a word (e.g., "-ing" in "walking").
* Root word: The base of a word, to which prefixes and suffixes can be added (e.g., "happy" in "unhappy").
* Stem: The core part of a word, which may include prefixes, suffixes, or both (e.g., "walk" in "walking").
* Affix: A general term for prefixes and suffixes.
The term you use depends on the specific context and the type of word part you are referring to.