1. Derivative: This is the most general term for a word formed from another word. It encompasses various methods of word formation, including:
* Suffixation: Adding a suffix to a base word (e.g., "happy" + "-ness" = "happiness")
* Prefixation: Adding a prefix to a base word (e.g., "un" + "happy" = "unhappy")
* Compounding: Combining two or more words (e.g., "sun" + "flower" = "sunflower")
* Conversion: Changing the grammatical function of a word without adding any affixes (e.g., "run" [verb] to "run" [noun])
2. Affixation: This specifically refers to the process of adding prefixes or suffixes to a base word.
3. Neologism: This refers to a newly coined word, which may or may not be derived from another word.
4. Back-formation: This is a specific type of word formation where a new word is created by removing a supposed suffix from an existing word. For example, "edit" was formed by removing the supposed "-or" from "editor."
5. Shortening: This refers to the process of creating a new word by shortening an existing one, often by removing syllables. For example, "exam" is a shortening of "examination."
The specific term that best fits depends on the context and how the new word is formed.