a necessary evil
Also found in: Acronyms.
necessary evil
Something bad that must exist or occur in order for something good to happen. These days, student loans are a necessary evil in order to get an education that leads to a well-paying job. Some view dictators as a necessary evil who keep the region stable by suppressing more radical elements.
a necessary evil
COMMON If you describe something as a necessary evil, you mean that although it is unpleasant, it is needed. He viewed war as a necessary evil. Managers sometimes think that training is a necessary evil that has to be done but is too expensive.
a necessary evil
something that is undesirable but must be accepted. 1997 Internet World Advertising may be a necessary evil. After all, someone has to support Internet ventures.