\Met"al*loid\, n. [L. metallum metal + -oid: cf. F.
m['e]tallo["i]de.]
   (a) Formerly, the metallic base of a fixed alkali, or
       alkaline earth; -- applied by Sir H. Davy to sodium,
       potassium, and some other metallic substances whose
       metallic character was supposed to be not well
       defined.
   (b) Now, one of several elementary substances which in the
       free state are unlike metals, and whose compounds
       possess or produce acid, rather than basic,
       properties; a nonmetal; as, boron, carbon, phosphorus,
       nitrogen, oxygen, sulphur, chlorine, bromine, etc.,
       are metalloids.

\Met"al*loid\, a.
1. Having the appearance of a metal.
2. (Chem.) Having the properties of a nonmetal; nonmetallic;
   acid; negative.