Prefixes, Suffixes and Root Words

When you read a word you have never seen before, you do not have to guess blindly. Many words are built from smaller pieces: a root word in the middle, and sometimes a prefix at the front or a suffix at the end. If you know what those pieces mean, you can figure out the whole word, even one you have never read before.

The root word is the main piece. It carries the biggest chunk of the meaning. For example, the root word in "unhelpful" is "help."

A prefix is a small piece added to the front of the root word. A suffix is a small piece added to the end of the root word. In "unhelpful," "un-" is the prefix and "-ful" is the suffix.

Each prefix has its own job. Once you know the job, you can use it to unlock new words.

"Un-" means "not" or "the opposite of." "Unsafe" means not safe.

"Re-" means "again." "Retell" means to tell again.

"Pre-" means "before." "Prepay" means to pay before something happens.

"Dis-" means "not" or "the opposite of." "Disagree" means to not agree.

"Mis-" means "wrongly" or "badly." "Misspell" means to spell a word wrongly.

Try this: if you read the word "disobey" and you already know "obey" means to follow the rules, you can use the prefix "dis-" to figure out that "disobey" means to not follow the rules.

Suffixes change a word's meaning too, and some of them also change how the word is used in a sentence.

"-Ful" means "full of." "Careful" means full of care.

"-Less" means "without." "Fearless" means without fear.

"-Able" means "can be done." "Washable" means it can be washed.

"-Ly" often tells how something happens. "Quickly" means done in a quick way.

"-Er" can compare two things, or it can mean "a person who does something." "Teacher" means a person who teaches, and "faster" means more fast than something else.

Try this: if you read "breakable" and you know "break" means to snap or shatter something, the suffix "-able" tells you that "breakable" means something that can break.

When you meet a word you do not know, try these three steps.

First, look in the middle of the word and find the root word you already know.

Second, check the front of the word for a prefix and the end of the word for a suffix.

Third, put the meanings together to make a guess, then read the guess back inside the sentence to check that it makes sense.

Let's try it with the word "unbreakable." The root word is "break." The prefix "un-" means "not," and the suffix "-able" means "can be done." Put together: "unbreakable" means "cannot be broken."

Root Word: The main part of a word that carries its core meaning, like "break" in "unbreakable."

Prefix: A word part added to the front of a root word, like "un-" or "re-."

Suffix: A word part added to the end of a root word, like "-ful" or "-able."

Unsafe: Not safe, using the prefix "un-" with the root word "safe."

Disagree: To not agree, using the prefix "dis-" with the root word "agree."

Misspell: To spell a word wrongly, using the prefix "mis-" with the root word "spell."

Fearless: Without fear, using the suffix "-less" with the root word "fear."

Washable: Able to be washed, using the suffix "-able" with the root word "wash."

Unbreakable: Cannot be broken, using the prefix "un-," the root word "break," and the suffix "-able" together.

Related lessons

• Root Prefixes and Suffixes