hairline

noun

1. a very slender line.
2. the lower edge of the hair, especially along the upper forehead: a hairline that slowly receded.
3. worsted fabric woven with very fine lines or stripes.
4. Printing.
   1. a very thin line on the face of a type.
   2. a style of type consisting entirely of such lines.
   3. a thin rule for printing fine lines.
   4. undesirable vertical lines between letters, caused by worn matrices.

adjective

5. narrow or fine as a hair: a hairline fracture.

noun

1. the natural margin formed by hair on the head
2. 1. a very narrow line
   2. (as modifier)a hairline crack
3. printing
   1. a thin stroke in a typeface
   2. any typeface consisting of such strokes
   3. thin lines beside a character, produced by worn or poorly cast type
4. a rope or line of hair

n.

“cord made of hair,” 1731, from hair + line. Meaning “a very fine line” is from 1846. As “the outline of the hair on top of the head,” by 1903. As an adjective, of cracks, etc., by 1923.

n.

1. The outline of the growth of hair on the head, especially across the front.