1. One that kills: a disease that was a killer of thousands; a killer of new ideas.
2. Slang Something that is extremely difficult to deal with or withstand: an exam that was a real killer.
1. Causing death or destruction: killer floods.
a. Having impressive or effective power or impact; formidable: had a killer smile; made killer profits.
b. Extremely useful or indispensible: a killer web application.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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