A root word is a word or word part that can form the basis of new words through the addition of prefixes and suffixes. Understanding the meanings of common roots can help you work out the meanings of new words as you encounter them.
Many of the words we use in our daily language come from a root word. Once you pull off any prefixes or suffixes, the root is usually what remains. For example, "egotist" has a root word of "ego" plus the suffix "-ist." "Acting" has the root word "act"; "-ing" is merely the suffix. In the examples of root words below, we'll examine the basic (root) word as well as its additions.