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.
There are some root words that can be used on their own or as part of other common words in the English language. The following root words are provided with their meaning and, in parentheses, a few examples of the root as part of other words:
Act: to move or do (actor, acting, reenact)
Arbor: tree (arboreal, arboretum, arborist)
Crypt: to hide (apocryphal, cryptic, cryptography)
Ego: "I" (egotist, egocentric, egomaniac)
Form: shape (conform, formulate, reform)
Legal: related to the law (illegal, legalities, paralegal)
Norm: typical (abnormal, normality, paranormal)
Phobia: fear (arachnophobia, claustrophobia, hygrophobia)
Since much of the English language is derived from Latin and Greek, there may be times when the root of a word isn't immediately recognizable because of its origin. You'll find that the roots listed below are from Greek or Latin and can't stand alone in English; they need something joined to them to make a whole word in English. Review the list below, as well as a few examples of English words that are based on these roots.
Acri: bitter (acrid, acrimony, acridity)
Astro: star (astronaut, astronomy, astrophysics)
Aud: hear (audience, audible, audio)
Auto: self (autonomy, autocrat, automatic)
Bene: good (benefactor, benevolent, beneficial)
Carn: flesh (carnal, carnivorous, reincarnate)
Corp: body (corporal, corporate, corpse)
Cred: believe (credible, credence, incredible)
Deca: ten (decade, decathlon, decalogue)
Dict: say (diction, dictate, edict)
Gen: birth (genesis, genetics, generate)
Lum: light (lumen, luminary, luminous)
Meter: measure (kilometer, millimeter, pedometer)
Micro: small (microbiology, microcosm, microscope)
Multi: many (multilingual, multiple, multifaceted)
Port: carry (portal, portable, transport)
Sect: cut apart (dissect, sectional, transect)
Sen: old (senator, senile, senior)
Sent: to feel (consent, sensation, sensing)
Tele: far (telephone, telegraph, television)
Vor: to eat greedily (herbivore, omnivore, voracious)
You could argue that roots like "sent" and "sect" can also stand alone as English words, but they have different meanings in that case. For more examples, explore these Greek and Latin Word Roots.
Whether talking with friends or reading a book, you're constantly bombarded with root words. Here are more examples of roots, their meanings, and other words that are formed by adding prefixes and/or suffixes to these language building blocks:
Ambul: to move or walk (amble, ambulance, ambulate)
Cardio: heart (cardiovascular, electrocardiogram, cardiology)
Cede: to go or yield (intercede, recede, concede)
Counter: against or opposite (counteract, counterpoint, counterargument)
Dem: people (democracy, democrat, demographic)
Derm: skin (dermatitis, dermatology, epidermis)
Equi: equal (equity, equilateral, equidistant)
Hypno: sleep (hypnosis, hypnotic, hypnotism)
Intra: within or into (intrapersonal, intramural, intravenous)
Ject: to throw (reject, eject, inject)
Magni: big or great (magnificent, magnify, magnitude)
Mal: bad (malignant, malfunction, malice)
Omni: all (omnipotent, omnipresent, omnivore)
Poly: many (polygamous, polygon, polytheist)
Script: to write (manuscript, postscript, scripture)
Vis, vid: to see (envision, evident, vision)
You probably noted that a couple of these words can either stand alone, such as "script" and "cede," or serve as the building block to longer, fuller words.
The terms "root words" and "base words" are often used interchangeably. The two are related, but they're not exactly the same thing.
A base word is a standalone English word that can also form other words with affixes (prefixes and suffixes). A root word is the Latin or Greek basis of a word that, generally speaking, can't be used as a standalone word. You may also see just "root" used to refer to the basic Greek or Latin word part that cannot stand alone.
For more on that, check out Are Base Words and Root Words the Same?
Every root word has a meaning and that meaning corresponds to the new word made from it. Be careful though, some root word combinations make less sense. Take the word "apology." Its root word logos means "speech" or "reason," and the prefix apo means "away from."
If you were to interpret the meaning of apology based on root words alone, you might think that it means "away from speech." That's not a very good explanation for a word that is used to express regret or remorse. So understanding the meaning of the roots can help you in general, but it won't always provide you with a clear definition.
To continue this compelling study, and learn more about the history of the words we use every day, check out some Roots of English Words Found in Greek Mythology.