- a very slender line.
- the lower edge of the hair, especially along the upper forehead: a hairline that slowly receded.
- worsted fabric woven with very fine lines or stripes.
- narrow or fine as a hair: a hairline fracture.
- the natural margin formed by hair on the head
- a very narrow line
- (as modifier)a hairline crack
- a thin stroke in a typeface
- any typeface consisting of such strokes
- thin lines beside a character, produced by worn or poorly cast type
- a rope or line of hair
- The outline of the growth of hair on the head, especially across the front.