Metalloids

noun

1. An element, such as silicon or germanium, intermediate in properties between that of a metal and a nonmetal; especially one that exhibits the external characteristics of a metal, but behaves chemically more as a nonmetal.
2. The metallic base of a fixed alkali, or alkaline earth; applied to sodium, potassium, and some other metallic substances whose metallic character was supposed to be not well defined.