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Common Roots and Prefixes

This lesson shows you how to use roots and prefixes you already know, such as un-, re-, bio, and aqua, as clues to figure out the meaning of unfamiliar words you meet while reading.

Introduction

You already know some roots and prefixes, even if you have never called them that. When you spot a part of a word that looks familiar, you can use it like a clue. This lesson builds on Greek and Latin Word Parts and shows you how to use those parts to figure out words you have never seen before.

What Is a Root? What Is a Prefix?

A root is the main part of a word. It holds the core meaning. A prefix is a small part added to the front of a root. A prefix changes or adds to the root's meaning.

Think of a root like the trunk of a tree and a prefix like a small branch you attach to it. The root "port" means "carry." Add the prefix "trans-" (across) and you get "transport," which means "to carry across."

Common Prefixes You Already Know

Here are some prefixes that show up again and again in English words.

un- means "not," as in unhappy (not happy)
re- means "again," as in replay (play again)
pre- means "before," as in preheat (heat before)
dis- means "opposite of," as in disagree (opposite of agree)
mis- means "wrongly," as in misspell (spell wrongly)
bi- means "two," as in bicycle (two wheels)
tri- means "three," as in triangle (three angles)

Common Roots You Already Know

Roots often come from Greek or Latin, but many are already hiding inside words you use every day.

bio means "life," as in biology (study of life)
graph means "write," as in autograph (self written signature)
tele means "far away," as in telephone (sound from far away)
aqua means "water," as in aquarium (place for water animals)
port means "carry," as in transport (carry across)
dict means "say," as in prediction (saying something before it happens)

How to Use Word Parts to Figure Out New Words

When you meet a word you do not know, look inside it for a root or prefix you recognize. Follow these steps.

Find a prefix or root inside the word that looks familiar.
Remember what that part means.
Put the meaning together with the rest of the word.
Reread the sentence to check if your guess makes sense.

Prefixes and roots combine to build the meaning of a whole word.

Try it with the word "aquanaut." You know "aqua" means water. If you know "naut" means sailor or traveler, you can guess that an aquanaut is someone who travels underwater. As you practice this often, you can move on to Roots, Prefixes, and Suffixes, where suffixes join the picture too.

Key Terms & Definitions

Root: the main part of a word that holds its core meaning.

Prefix: a word part added to the front of a root that changes its meaning.

Unhappy: not happy, combining the prefix un- with the root happy.

Transport: to carry across, combining the prefix trans- with the root port.

Biography: the story of a life, combining the root bio with the root graphy.

Aquanaut: someone who travels underwater, combining the root aqua with naut.

Practice Activities

Pick a word you do not know from a book you are reading. Look for a prefix or root inside it, write down what that part means, and guess the whole word's meaning. Then check a dictionary to see how close your guess was.

You can also make word part cards. Write a prefix like re- or un- on one card and a root like port or bio on another. Mix and match the cards to build new words and explain what each one might mean. For more root word practice, try Word Roots for Vocabulary Building.

Related lessons

Greek and Latin Word Parts