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Root Words: Definition, Lists & Examples

Updated on January 21, 2024Grammar

Have you noticed that some words—like act, react, and action—include the same parts as other words? These repeated parts are root words, and they’re one of the most important building blocks of the English language.

This article explains how root words work in English. We discuss root words’ prefixes and suffixes, how root words work, and how they’re different from base words. We even list some common root word examples so you can learn to recognize them.

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What are root words?

Root words are a type of morpheme (small part of a word) with a distinct meaning that can combine with affixes to create new words or sometimes act alone as independent words. Root words are instrumental in grammar for forming words, and understanding their meanings can help you define new words with those same roots.

Take, for example, the root word legal. On its own, it’s an independent word (an adjective) that means “required or permissible by law.” You can combine legal with common prefixes and suffixes to create new words, like illegal or legalize. Although these words each have a different definition and word class, their meanings all relate to the law because they share the same root word.

Keep in mind that root words aren’t always independent words. Sometimes root words are bound morphemes, which means they require additional affixes to form a complete word. Take the root word ject, for example. Alone, ject is not a word, but if you combine it with the right affixes, you can create real words like reject, eject, or interject.

Root words in English: How do they work?

Of course English is English, but it’s also Greek, Latin, French, Algonquian, Polynesian . . . Thanks to loan words, English uses a lot of parts from other languages, and these parts are often used as root words.

In particular, a lot of English root words come from ancient Latin and Greek. Over the past couple of millennia, their grammar and spelling have changed; however, the meanings of some root words are still recognizable today by the words they create. For example, the Latin word for water, aqua, is still used as a root for modern-day words related to water, like aquarium or aquatic.

Root words also play a major role in verb conjugation. With regular verbs, some tenses like the simple past add a special affix to the verb. For example, the past tense of the verb play uses the suffix –ed to create played. The root (play) is the same in both words, but the words themselves have slightly different meanings.

Sometimes the root word changes slightly when used in another word. Take the root words describe and noise, which use different spellings and/or sounds for the variant words description and noisy, respectively. These changes often occur because different sounds match better with certain affixes or just through the natural evolution of language over hundreds of years.

Root words: prefixes and suffixes

Root words often combine with prefixes, affixes that come at the beginning of a word, and suffixes, affixes that come at the end of a word. By using different prefixes and suffixes, you can change both the meaning of the root and its word class.

For example, adding prefixes like dis– and un- reverses the meaning of the root word, like in the words disbelief or uncertain, which mean the opposite of their root words belief and certain, respectively. Likewise, suffixes can often change the word class: The suffix -ion can change the verb root act into the noun action.

What gets confusing is when root words also act like affixes. Take the root word astro, from the ancient Greek word for “star.” Alone, astro is not a word, but you can combine it with other affixes to make complete words, like astronomy or astronaut. In this sense, astro can simultaneously be a root word and an affix.

Root word examples


  • civil
  • civilization
  • uncivilized
  • civic


  • friendly
  • unfriendly
  • friendship
  • befriend


  • document
  • indoctrinate
  • doctor
  • documentary


  • value
  • evaluate
  • valor
  • valid


  • terrain
  • extraterrestrial
  • subterranean
  • territory


  • transportation
  • portable
  • import/export
  • portal


  • general
  • gender
  • generic
  • generate
  • genre


  • audio
  • audience
  • inaudible
  • audition


  • describe/description
  • transcribe/transcription
  • manuscript
  • scribble


  • bicycle
  • motorcycle
  • cyclist
  • cyclical

Root words vs. base words

Root words are often confused with base words not only because their meanings are similar, but also because sometimes they’re the same.

A base word is a word within another word that defines its meaning, not unlike a root word. The difference between root words and base words is that base words can always stand alone as independent words, but root words are sometimes incomplete on their own.

For example, take the word unfriendly; both the root word and the base word are the same: friend. The prefix un– and the suffix –ly slightly modify the meaning and word class, but the core morpheme, friend, is both the root and the base. On its own, friend is still a word, so it qualifies as a base word.

However, look at another example: the word disrupt. The root word is rupt, which we also see in other words like interruption and rupture. However, rupt alone is not a complete word, so it cannot be a base word. In fact, the word disrupt doesn’t have a base word, only a root word.

Root word FAQs

What are root words?

Root words are a type of morpheme (small part of a word) with a distinct meaning that can combine with affixes to create new words or sometimes act alone as independent words. Root words are instrumental in grammar for forming words, and understanding their meanings can help you define new words with those same roots.

How do root words in English work?

Root words combine with different prefixes and suffixes for different meanings and word classes. For example, the root word act can combine with the prefix re- to create a new word react or with the suffix –ion to create action. Although act, react, and action are all different words, their meanings are all related, thanks to the shared root word.

What are some root word examples?

One common root word in English is terr, which comes from the Latin word terra, which means “earth.” Using different prefixes and suffixes, the root word terr can become terrain, territory, extraterrestrial, and subterranean, among others. More root word examples include civ (civilization, civic), audi (inaudible, audience), and port (transportation, portable).

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