quintant

noun2

1. •
   (rare) A fifth of a circle.

   • The dome rests on five pylons, equally spaced at 72°; two of the five quintants embrace the office building. — 1959
2. •
   (historical) An instrument used for measuring angular distance, capable of measuring angles of up to 72 or 144 degrees.

   • In former days octants, quintants and quadrants were in general use. The only basic difference between these instruments and the sextant is in the length of the arc. — 1944