From The Collaborative International Dictionary of English v.0.48 [gcide]:
Nonmetallic \Non`me*tal"lic\, a.
1. Not metallic.
[1913 Webster]
2. (Chem.) Resembling, or possessing the properties of, a
nonmetal or metalloid; as, sulphur is a nonmetallic
element.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
nonmetallic
adj 1: not containing or resembling or characteristic of a
metal; "nonmetallic elements" [syn: nonmetallic,
nonmetal] [ant: {metal(a)}, metallic]