Question

What is affix?

A word that sounds the same as another word
the beginning of a word
A word part added to the beginning or end of a word
The base part of a word

Answer 1

An affix is a word part added to the beginning or end of a word.
Affix is a term which includes prefixes (word parts added to the beginning of a word) and suffixes (word parts added to the end of a word). Affixes are used when you want to create a new word out of an old one. For example:
to imagine (verb) + -ation (suffix) = imagination (noun)
pre- (prefix) + determined (adjective) = predetermined (adjective)