Page 2 Word Knowledge Study Guide for the ASVAB

Skills to Practice

Prefixes, Suffixes, and Roots

With thousands of words in the English language, one way to prepare for this part of the exam is to revisit some concepts you may remember from school: prefixes, suffixes, and roots. Focusing your energy on word parts may help you tackle words you have never encountered before.


A prefix is a part of a word that affixes to the front of a root word (defined below) to create a new meaning or change the overall meaning of the root. Although you may not know it, prefixes are common and may be found in everyday speech.

The most common prefixes include:

un- , as in unhappy (not happy)
re- , as in return (come back)
dis- , as in disgrace (loss of respect)
mis- , as in misuse (use incorrectly)
semi- , as in semiformal (somewhat formal)
anti- , as in antisocial (prone to avoiding socializing)

For example, if you know the prefix omni means all, you will have an easier time figuring out that the word omnipotent means all-powerful.


A suffix is the opposite of a prefix; rather than affixing to the beginning of a root word, a suffix is placed at the end of a root word to alter the root word’s meaning. The most common suffixes include:

-able, as in comfortable (able to feel comfort)
-ed, as in comforted (past-tense comfort)
-er, as in stronger (has more strength)
-est, as in strongest (has the greatest amount of strength)
-ful, as in beautiful (full of beauty)
-ing, as in singing (present tense of sing)
-less, as in fearless (without fear)
-ly, as in slowly (in a slow manner)
-ous, as in courageous (full of courage)

For example, if you have learned that the suffix or means “one who does a thing,” and you recognize the root word bene means “good,” the word benefactor becomes much easier to break down: good + someone who does something = a person who gives help or money to another person or cause (benefactor).

Root Word

Root words are words that are devoid of prefixes and suffixes and stand on their own in meaning. The word beautiful, for instance, contains the root word beauty. This word can stand alone and have its own meaning, but it can also be combined with suffixes and prefixes to create a new meaning.

Root words typically have either Greek or Latin origins, though a few come from Germanic languages. For instance:

The words morph and path have Greek origins and mean “form” and “feeling,” respectively. Each is seen commonly in the English language, in words such as mesomorph and empath.

The words arbor and aqua have Latin origins and mean “tree” and “water,” respectively, and can be found in words such as arborous and aqueduct.

Knowing the meaning of a root word and the most common prefixes and suffixes can lend tremendous insight into the overall meaning of a word or phrase.

If you can’t immediately spot the root word, try dropping a few of the letters from either the beginning or end. The root word cede means to “go or yield” and can plainly be found in the word recede by dropping the first two letters.