Answer:

knurls

Answer	Crossword Clue
KNURLS	Thumbscrew ridges
KNURLS	Small ridges, as on a thumbscrew.
KNURLS	Knots in wood

KNURLS	Coin-edge ridges

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.