A thin stroke usually common to serif typefaces.
Definition: In typeface anatomy, a hairline is the thinnest stroke found in a specific typeface that consists of strokes of varying widths. Hairline is often used to refer to a hairline rule, the thinnest graphic rule (line) printable on a specific output device. Hair or hairline is also a type of serif, the minimum thickness for a serif.
Also Known As: hair stroke
a fine line connecting thicker strokes in a printed letter