met·al·loid 
(mĕtl-oid′)
(mĕtl-oid′)n.
1. A nonmetallic element, such as arsenic, that has some of the chemical properties of a metal. Most metalloids behave as semiconductors.
2. A nonmetallic element, such as carbon, that can form an alloy with metals.
adj. also met·al·loi·dal (mĕt′l-oidl)
1. Relating to or having the properties of a metalloid.
2. Having the appearance of a metal.