Definition of "knife-edge" []

• A sharp cutting edge. (noun)
• A sharp, narrow edge or border: "saying lines that teeter on the knife-edge between literature and lunacy” ( Vincent Canby). (noun)
• A wedge of metal used as a low-friction fulcrum for a balancing beam or lever. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "And after Davies gives a number of remarkable facts about the incredible fine-tuning of the universe, he adds, “The cliché that “life is balanced on a knife-edge” is a staggering understatement in this case: no knife in the universe could have an edge that fine.”"
• "He wears black clothes, pants creased to a knife-edge, loose shirts with mandarin collars."
• "One of the more irritating tropes in economic journalism is the "knife-edge" metaphor."