Är'/mil, n.

n. [Lat. armilla, a bracelet, from armus, arm.] An ancient astronomical instrument; when composed of one ring placed in the plane of the equator for determining the time of the equinoxes, called an equinoctial armil; when of two or more rings, one in the plane of the meridian, for observing the solstices, called a solstitial armil. Whewell.