Ar"mil (#), n. [L. armilla a bracelet, fr. armus arm: cf. OF. armille.]
An ancient astronomical instrument.
⇒ 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.
© Webster 1913.