\Ar"mil\, n. [L. armilla a bracelet, fr. armus arm: cf.
OF. armille.]
1. A bracelet. [Obs.]
2. An ancient astronomical instrument.
Note: When composed of one ring placed in the plane of the
      equator for determining the time of the equinoxes, it
      is called an equinoctial armil; when of two or more
      rings, one in the plane of the meridian, for observing
      the solstices, it is called a solstitial armil.
      --Whewell.