Common Prefixes:
* Anti-: against, opposite (antibiotic, anti-war)
* Bi-: two, twice (bicycle, bilingual)
* Co-: together, with (co-worker, cooperate)
* Dis-: not, opposite (disagree, disappear)
* Ex-: out of, former (exit, ex-president)
* In-: in, into (inside, inactive)
* Mis-: wrong, badly (misunderstand, misspell)
* Pre-: before, beforehand (pre-game, pre-school)
* Re-: again, back (redo, re-read)
* Sub-: under, below (submarine, subway)
* Tri-: three (triangle, tri-color)
* Un-: not, opposite (unhappy, unable)
Less Common Prefixes:
* Dia-: through, across (diameter, diagonal)
* Epi-: upon, on (epidermis, epicenter)
* Eu-: good, well (euphoric, eulogy)
* Geo-: earth (geography, geophysics)
* Hyper-: above, excessive (hyperactive, hyperbole)
* Hypo-: under, below (hypothermia, hypoglycemia)
* Inter-: between, among (internet, intergalactic)
* Intra-: within (intravenous, intramural)
* Peri-: around, near (perimeter, periscope)
* Poly-: many (polyglot, polygon)
* Pro-: forward, in favor of (proactive, pro-choice)
* Semi-: half, partly (semicircle, semi-conscious)
* Super-: above, beyond (superhuman, supermarket)
Remember: Some prefixes can have multiple meanings, and the context will help determine the intended meaning.