Main Entry: hair·line

Pronunciation: \-ˈlīn\

Function: noun

Date: 1846

1 : a very slender line: as a : a tiny line or crack on a surface <a hairline bone fracture> b : a fine line connecting thicker strokes in a printed letter
2 : hairbreadth
3 a : a textile design consisting of lengthwise or crosswise lines usually one thread wide b : a fabric with such a design
4 a : the outline of scalp hair especially on the forehead b : the way the hair frames the face

— hairline adjective