Answer: Affix.
An affix is a grammatical unit that is attached to a word's stem to form a new word. They are important in English because they are one of the main ways in which the language creates new words.
The two most common ones are: prefixes, which are placed before the stem (ex. pre-, in-, un-) and suffixes, which are placed after the stem (ex. -ly, -ness).
<span>-She was burnt when the family home caught fire.</span>
