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.
  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.


narrow or fine as a hair: a hairline fracture.

Origin of hairline

First recorded in 1725–35; hair + line1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for hairline

Contemporary Examples of hairline

Historical Examples of hairline

  • He readjusted the slide rule and slid the hairline over a bit.

    Islands of Space

    John W Campbell

  • The hairline above his ear was a simpler curve than she recalled.

    Wilderness of Spring

    Edgar Pangborn

  • He inspected the base of the hook closely and there seemed to be a fine, hairline fracture appearing around it.

  • There was a lot of grey in his short hair, and his hairline was a lot higher up his forehead.


    Cory Doctorow

  • In the sunlight it gleamed like polished silver, but they could see a hairline break in the metal encircling the center portion.

    Gold in the Sky

    Alan Edward Nourse

British Dictionary definitions for hairline



the natural margin formed by hair on the head
  1. a very narrow line
  2. (as modifier)a hairline crack
  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
a rope or line of hair
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for hairline

"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.

Online Etymology Dictionary, © 2010 Douglas Harper

hairline in Medicine




The outline of the growth of hair on the head, especially across the front.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.