An archaic Unit Fraction variously defined as 1/200 (of an hour ), 1/10 or 1/12 (of an inch ), 1/12 (of a celestial body's angular diameter), or 1/60 (of an hour or Degree).
), 1/10 or 1/12 (of an
inch 
), 1/12 (of a celestial body's angular diameter), or 1/60 (of an hour or Degree).