n. (Chem.) Any one of three metameric radicals, CH2.C6H4.CH2, derived respectively from the three xylenes. Often used adjectively; as, xylylene alcohol. [ 1913 Webster ]
n. [ Gr. xy`lon wood. ] (Bot.) That portion of a fibrovascular bundle which has developed, or will develop, into wood cells; -- distinguished from phloem. [ 1913 Webster ]