razor blade

Short definition from Wiktionary

Noun

1. 1
   A thin piece of steel with a sharp edge that can be fitted into a razor.
2. 2
   A replaceable cartridge in which razor blades are set, fitted into a razor.
3. 3
   A thin interchangeable blade for a utility knife (especially, that of a Stanley knife) that is similar to a razor blade stricto sensu (in size, thinness, and sharpness).
4. 4
   Alternative form of razor blade.

Verb

1. 1
   Alternative form of razor-blade.
2. 2
   To cut or scrape with a razor blade or something similar.
3. 3
   To do something with extreme precision.