This list contains some of the common roots and prefixes that make up the building blocks of numerous English words. Following the table of general roots and prefixes is a table of number prefixes.
The very words prefix and suffix are good examples, too. Pre means before and fix means to fasten or attach, so a quite literally, a prefix is something attached to something else. Suf is a variant of sub, below or under, so a suffix is something fastened underneath something else (in this case, behind the root).
By learning the common roots and prefixes (and a few suffixes) you will be able to discern the meaning of many new words almost immediately. (But do look them up for confirmation.)
| Root or Prefix | Meaning | Examples |
| a, an | not, without | atheist, anarchy, anonymous apathy, aphasia, anemia, atypical, anesthesia |
| ab | away from | absent, abduction, aberrant, abstemious, abnormal, abstract, absorb |
| acro | high, tip, top | acrobat, acrophobia, acronym, acromegaly |
| ad | to, toward | admit, addition, advertisement, adherent, admonish, address, adhesive, adept, adjust |
| alt | high | altitude, altimiter, alto, contralto, altocumulus |
| ambul | to walk | ambulatory, amble, ambulance, somnambulist, perambulate, preamble |
| ante | before | anteroom, antebellum, antedate antecedent, antediluvian |
| anti, ant | against, opposite | antisocial, antiseptic, antithesis, antibody, antichrist, antinomies, antifreeze, antipathy, antigen, antibiotic, antidote, antifungal, antidepressant |
| audi | to hear | audience, auditory, audible, auditorium, audiovisual, audition, audiobook |
| auto | self | automobile, automatic, autograph, autonomous, autoimmune, autopilot, autobiography |
| be | thoroughly | bedecked, besmirch, besprinkled, begrudge, begrime, belie, bemoan |
| bell | war | belligerent, antebellum, bellicose, rebel |
| bene | good, well | benefactor, beneficial, benevolent, benediction, beneficiary, benefit |
| bi | two | bicycle, bifocals, biceps, billion, binary, bivalve, bimonthly, bigamy, bimetal, biathlete, bicarbonate |
| cede, ceed, cess | to go, to yield | succeed, proceed, precede, recede, secession, exceed, succession, excess |
| chron | time | chronology, chronic, chronicle, chronometer, anachronism |
| cide, cis | to kill, to cut | fratricide, suicide, incision, excision, circumcision, precise, concise, precision |
| circum | around | circumnavigate, circumflex, circumstance, circumcision, circumference, circumorbital, circumlocution, circumvent, circumscribe, circulatory |
| clud, clus claus | to close | include, exclude, clause, claustrophobia, enclose, exclusive, reclusive, conclude, preclude |
| con, com | with, together | convene, compress, contemporary, converge, compact, confluence, concatenate, conjoin, combine, convert, compatible, consequence |
| contra, counter | against, opposite | contradict, counteract, contravene, contrary, counterspy, contrapuntal, contraband |
| cred | to believe | credo, credible, credence, credit, credential, credulity, incredulous, creed, incredible |
| cycl | circle, wheel | bicycle, cyclical, cycle, encliclical, motorcycle, tricycle, cyclone |
| de | from, down, away | detach, deploy, derange, deodorize, devoid, deflate, degenerate, deice, descend, derail, depress, depart, decompose, destruction |
| dei, div | God, god | divinity, divine, deity, divination, deify |
| demo | people | democracy, demagogue, epidemic, demographic |
| dia | through, across, between | diameter, diagonal, dialogue, dialect, dialectic, diagnosis, diachronic, diagram, diaphragm |
| dict | speak | predict, verdict, malediction, dictionary, dictate, dictum, diction, indict, contradict |
| dis, dys, dif | away, not, negative | dismiss, differ, disallow, disperse, dissuade, disconnect, dysfunction, disproportion, disrespect, distemper, distaste, disarray, dyslexia |
| duc, duct | to lead, pull | produce, abduct, product, transducer, viaduct, aqueduct, induct, deduct, reduce, induce |
| dyn, dyna | power | dynamic, dynamometer, heterodyne, dynamite, dynamo, dynasty |
| ecto | outside, external | ectomorph, ectoderm, ectoplasm, ectopic, ectothermal |
| endo | inside, withing | endotoxin, endoscope, endogenous |
| equi | equal | equidistant, equilateral, equilibrium, equinox, equitable, equation, equator |
| e, ex | out, away, from | emit, expulsion, exhale, exit, express, exclusive, enervate, exceed, explosion |
| exter, extra | outside of | external, extrinsic, exterior, extraordinary, extrabiblical, extracurricular, extrapolate, extraneous, exterminator, extract, extradite, extraterrestrial, extrasensory, extravagant, extreme |
| flu, flux | flow | effluence, influence, effluvium, fluctuate, confluence, reflux, influx |
| flect, flex | to bend | flexible, reflection, deflect, circumflex, inflection, reflex |
| graph, gram | to write | polygraph, grammar, biography, graphite, telegram, autograph, lithograph, historiography, graphic, electrocardiogram, monogram |
| hetero | other | heterodox, heterogeneous, heterosexual, heterodyne |
| homo | same | homogenized, homosexual, homonym, homophone |
| hyper | over, above | hyperactive, hypertensive, hyperbolic, hypersensitive, hyperventilate, hyperkinetic, hyperlink, hypertext, hypersonic, hypertrophy |
| hypo | below, less than | hypotension, hypodermic, hypoglycemia, hypoallergenic, hypothermia, hypothesis |
| in, im | not | inviolate, innocuous, intractable, innocent, impregnable, impossible |
| infra | beneath | infrared, infrastructure, infrasonic |
| inter, intro | between | international, intercept, intermission, interoffice, internal, intermittent, introvert, introduce |
| intra | within, into | intranet, intracranial, intravenous, intramural, intramuscular, intraocular |
| jac, ject | to throw | reject, eject, project, trajectory, interject, dejected, inject, ejaculate |
| mal | bad, badly | malformation, maladjusted, dismal, malady, malcontent, malfeasance, maleficent, malevolent, malice, malaria, malfunction, malignant |
| mega | great, million | megaphone, megalomaniac, megabyte, megalopolis |
| meso | middle | mesomorph, mesoamerica, mesosphere |
| meta | beyond, change | metaphor, metamorphosis, metabolism, metahistorical, metainformation, metacognitive |
| meter | measure | perimeter, micrometer, ammeter, multimeter, altimeter, geometry, kilometer |
| micro | small | microscope, microprocessor, microfiche, micrometer, micrograph |
| mis | bad, badly | misinform, misinterpret, mispronounce, misnomer, mistake, misogynist |
| mit, miss | to send | transmit, permit, missile, missionary, remit, admit, missive, mission |
| morph | shape | polymorphic, morpheme, amorphous, metamorphosis, morphology, morphing |
| multi | many | multitude, multipartite, multiply, multipurpose, multicolored, multimedia, multinational |
| neo | new | neologism, neonate, neoclassic, neophyte |
| non | not | nonferrous, nonabrasive, nondescript, nonfat, nonfiction, nonprofit, nonsense, nonentity |
| omni | all | omnipotent, omnivorous, omniscient, omnibus, omnirange, omnipresent |
| para | beside | paraprofessional, paramedic, paraphrase, parachute, paralegal, parallel, comparison |
| per | through, intensive | permit, perspire, perforate, persuade, perceive, perfect, permit, perform |
| peri | around | periscope, perimeter, perigee, periodontal |
| phon | sound | telephone, phonics, phonograph, phonetic, homophone, microphone |
| phot | light | photograph, photosynthesis, photon |
| poly | many | polytheist, polygon, polygamy, polymorphous |
| port | to carry | porter, portable, report, transportation, deport, import, export |
| re | back, again | report, realign, retract, revise, regain, reflect, rename, restate, recombine, recalculate, redo |
| retro | backwards | retrorocket, retrospect, retrogression, retroactive |
| sanct | holy | sanctify, sanctuary, sanction, sanctimonious, sacrosanct |
| scrib, script | to write | inscription, prescribe, proscribe, manuscript, conscript, scribble, scribe |
| sect, sec | cut | intersect, transect, dissect, secant, section |
| semi | half | semifinal, semiconscious, semiannual, semimonthly, semicircle |
| spect | to look | inspect, spectator, circumspect, retrospect, prospect, spectacle |
| sub | under, below | submerge, submarine, substandard, subnormal, subvert, subdivision, submersible, submit |
| super, supra | above | superior, suprarenal, superscript, supernatural, supercede, superficial, superhero, superimpose |
| syn | together | synthesis, synchronous, syndicate, synergy, snyopsis, syncretism |
| tele | distance, from afar | television, telephone, telegraph, telemetry, telepathy |
| theo, the | God | theology, theist, polytheist, pantheism, atheist |
| therm, thermo | heat | thermal, thermometer, thermocouple, thermodynamic, thermoelectric |
| tract | to drag, draw | attract, tractor, traction, extract, retract, protract, detract, subtract, contract, intractable |
| trans | across | transoceanic, transmit, transport, transducer |
| un | not | uncooked, unharmed, unintended, unhappy |
| veh, vect | to carry | vector, vehicle, convection, vehement |
| vert, vers | to turn | convert, revert, advertise, versatile, vertigo, invert, reversion, extravert, introvert |
| vita | life | vital, vitality, vitamins, revitalize |
| Prefix | Meaning | Examples |
| mono, uni | one | monopoly, monotype, monologue, mononucleosis, monorail, monotheist, unilateral, universal, unity, unanimous, uniform |
| bi, di | two | divide, diverge, diglycerides, bifurcate, biweekly, bivalve, biannual, billion |
| tri | three | triangle, trinity, trilateral, triumvirate, tribune, trilogy, tricycle, trillion |
| quat, quad | four | quadrangle, quadruplets, quaternary, quarter, quadrillion |
| quint, penta | five | quintet, quintuplets, pentagon, pentane, pentameter, quintillion |
| hex, ses, sex | six | hexagon, hexameter, sestet, sextuplets, sextillion |
| sept | seven | septet, septennial, septillion |
| oct | eight | octopus, octagon, octogenarian, octave, octillion |
| non | nine | nonagon, nonagenarian, nonillion |
| dec | ten | decimal, decade, decalogue, decimate, decillion |
| cent | hundred | centennial, century, centipede, centillion |
| mill, kilo | thousand (10^3) | millennium, kilobyte, kiloton |
| mega | million (10^6) | megabyte, megaton, megaflop |
| giga | billion (10^9) | gigabyte, gigaflop |
| tera | trillion (10^12) | terabyte, teraflop |
| peta | quadrillion (10^15) | petabyte |
| exa | quintillion (10^18) | exabyte |
| zetta | sextillion (10^21) | zettabyte |
| yotta | septilion (10^24) | yottabyte |
| milli | thousandth (10^-3) | millisecond, milligram, millivolt |
| micro | millionth (10^-6) | microgram, microvolt |
| nano | billionth (10^-9) | nanosecond, nanobucks |
| pico | trillionth (10^-12) | picofarad, picocurie |
| femto | quadrillionth (10^-15) | femtosecond |
| atto | quintillionth (10^-18) | attosecond, attometer |
| zepto | sextillionth (10^-21) | zeptosecond |
| yocto | septillionth (10^-24) | yoctosecond |
End note: In my second year of Latin in high school, we were required to find twenty-five Latin word roots and for each root to find five English words containing the root. This exercise not only helped to increase my vocabulary, but it gave me a valuable insight into the way many English words are constructed. As technology advances, new words are coined to cover some new idea or thing, and often these words are created from existing roots. A little root knowledge here can therefore help us to begin to understand a new word even before we read about its meaning.