Apr 9, 2025 metalloid ˈme-tə-ˌlȯid 3 syllables very rare ‹ noun. an element intermediate in properties between the typical metals and nonmetals noun. a nonmetal that can combine with a metal to form an alloy adjective. resembling a metal adjective. of, relating to, or being a metalloid › Origin metall-, form in derivation of + , after German Metalloide & French métalloïde.