“necessary evil” is something unpleasant or undesirable that people accept because it is considered necessary for a particular result.
ReviewedEvidence1 sourceSectionPhrases & Idioms
Quick answer
A “necessary evil” is something unpleasant or undesirable that people accept because it is considered necessary for a particular result.
Key details
Canonical Formnecessary evil
Core Meaningsomething unpleasant that is accepted because it is needed to achieve a result
Further guidance
Contextual Examples
The extra verification step was treated as a necessary evil to reduce fraud.
Calling routine paperwork a necessary evil signals dislike as well as acceptance.
History Boundary
Current dictionary-supported meaning is published without claiming an exact inventor, coinage date, or absolute first use.
Meaning
something unpleasant that is accepted because it is needed to achieve a result
Meaning Boundary
The phrase expresses reluctant acceptance; it does not mean the thing is literally evil in a moral or legal sense.
Practical Use
Use it for something undesirable that is accepted because it is considered necessary for a desired result.
Tone Boundary
Evaluative and somewhat informal; formal reports may be clearer if they state the cost and necessity directly.
Usage Boundary
The phrase expresses reluctant acceptance: calling something a necessary evil does not mean it is good, only that the speaker sees it as needed for an outcome.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
“Between a rock and a hard place” describes being trapped in a very difficult situation that requires a hard choice. This guide publishes the current meaning supported by Cambridge and does not add an unsupported exact-origin chronology.
A “can of worms” is a complicated situation that produces many further problems when you begin to deal with it. Cambridge marks the idiom informal. Use it for a problem that opens into further complications, not merely for a single isolated difficulty.
A “Catch-22” describes an impossible situation in which one requirement depends on another condition that cannot be met first. Use it for a self-defeating dependency or circular trap, not merely for any difficult choice or ordinary dilemma.
“Come hell or high water” expresses strong determination to proceed despite difficulties or obstacles. It is emphatic and informal, so its tone may be stronger than needed in neutral professional prose.
“Come rain or shine” expresses commitment or certainty despite changing conditions. It can refer literally to weather, but its ordinary idiomatic use is broader: something will happen regardless of difficulties or circumstances.
“Cross that bridge when we come to it” means deal with a possible problem if and when it actually arises instead of worrying about it in advance. An 1851 Longfellow text directly preserves an older negative form and explicitly calls it an old proverb.
Double bind describes a trap created by incompatible expectations or choices. In ordinary writing it can describe a practical dilemma; specialist psychological uses can carry narrower theoretical meanings.
“Face the music” means accept criticism, punishment, or responsibility for something you have done. The guide gives the current meaning without attaching an unsupported exact origin date.
