barleycorn

plural barleycorns

1. agricultureA grain of barley.

   The Town Mouse came, and they sat down to a dinner of barleycorns and roots, the latter of which had a distinctly earthy flavour.

   1912, V.S. Vernon Jones, Aesop's Fables

2. obsoleteThe length of such a grain; a unit of length of approximately one third (or sometimes one quarter) of an inch or eight millimetres, still used as a basis for shoe sizes.

   This trip to Italy has actually enlarged the diameter of my head thirteen barleycorns!

   1879, Geo. Alfred Townsend, Bohemian Days

   1 more example

   Then shewed the devil the booke unto the friar, and the friar saw it was an uncut unique of incalculable value; the height of it was half a cubit and the breadth of it the fourth part of a cubit and the thickness of it five barleycorns lacking the space of three horsehairs.

   1907, Various, The Wit and Humor of America, Volume IV. (of X.)

3. architectureA small groove between two moldings.