Noun: knurl nurl- A small protuberance, ridge, or node on a surface, often part of a series for grip
"The knurls on the screwdriver handle provided a better grip"
Verb: knurl nurl- Provide with ridges or a roughened surface to improve grip
"They knurled the edges of the coin"
Derived forms: knurled, knurling, knurls
Encyclopedia: Knurl