Words that aren’t opposites
- real — unreal
- canny — uncanny
- valuable — invaluable
- credulous — incredulous
- fact — fiction (this is actually a deep one. Roots of both are in proto-indo-european words for “to make”)
- mure — demure
- vert — invert
- aging — imaging
- pact — impact
- mediate — immediate
- predate — postdate
- toward — untoward
Prefixed words that aren’t words and don’t have prefixes. Some of these are words that aren’t opposites because one of them isn’t a word.
- ert — inert
- molish — demolish
- venient — convenient
- dundant — redundant
- fluous — superfluous
- becile — imbecile
- agining — imagining
- plicate — replicate
- gruntled — disgruntled
- sidious — insidious
- whelmed — overwhelmed
- rageous — outrageous
- cursion — recursion
- imburse — reimburse
- burse — reimburse
- fluous — superfluous
- cilious — supercilious
- quited — requited
- quited — unrequited
- vagant — extravagant
- bolé — hyperbole
- bolic — hyperbolic
- luctant — reluctant
- hap — mishap
- pugnant — repugnant
- dolent — redolent
- eptitude — ineptitude
Also, words with redundant prefixes, and
- reiterate — iterate
- concatenate — catenate
- intercatenate — catenate
- encompass — compass
- eminant — preeminant
- perception — apperception
Other fixed words whose meanings don’t correspond to those of their bases
- irrespective
- consummate
- insure
- ensure
- fulsome
- remiss
- relax
- reply
- reflux
- reflex
- convent
- effable
This post was formerly “Words that aren’t opposites,” but it’s bigger now. Obviously, there’s room for more.
See also, islands that don’t exist, and list of fictional guidebooks.