Question

which word part is added to and affix to make a new word
a prefix
a letter
a root
or a suffix

Answer 1

A word part that is added to a base word to create a new word is called an **affix**. Affixes can be either prefixes or suffixes. A **prefix** is added at the beginning of a word (e.g., "un-" in "unhappy"), while a **suffix** is added at the end (e.g., "-ness" in "happiness").

So, to answer your question, both a prefix and a suffix are types of affixes that are added to a root word to form new words.