Prefix Definitions Examples
Negative Prefixes
a not or without amoral, apolitical,atheist, atypical
anti against antitrust, antisocial, antifreeze, antibody
dis opposite of disbelief, distrust, disuse, distaste
in/im not independent, inexcusable, inerrant immature impossible
mis badly wrongly misbehave, mislead, misuse, mistrust
un not unbelievable, untrustworthy, uncooked, unchanged

Prefixes Showing Amounts

mono one, single monocle, monologue, monogamy, monopoly
uni one unicycle, unisex,unit
bi,du two bicycle, biped, duet, dual, duplex
tri three tricycle, tripod, triathlon, triplet
quadr four quadruple, quadrant, quadruplet quadruped
multi many multiplex, multitude, multivitamin, multicultural
semi half semicircle, semifinal, semiannual, 

Prefixes that Show Places and Directions

ad toward adjoin, advance
ante before/front antecedent, antebellum, antechamber
circum around circumvent, circumference, circumnavigate
post after postlude, postdate, postpone, post
sub under submarine, subzero, subsoil
re back/again redo, repaint, repeal, repeat
retro back  retroactive, retro
trans across over transmit, transatlantic, transplant