knurl vs protrusion

knurl

• A lined or crossgrained pattern of ridges or indentations rolled or pressed into a part for grip. 

• A crossgrained protuberance; a nodule; a boss or projection. 

• A contorted knot in wood. 

• To roll or press a pattern of ridges or indentations into a part for grip. 

protrusion

• The act of protruding. 

• The state of being protruded. 

• Anything that protrudes.