n. One of the natural groups, more important than an order, into which some classes are divided; as, the angiospermous subclass of exogens. [ 1913 Webster ]
a. [ Pref. sub- + L. clavis a key. See Clavicle. ] (Anat.) Situated under the clavicle, or collar bone; as, the subclavian arteries. [ 1913 Webster ]