zirconium

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A lustrous, grayish-white, strong, ductile metallic element obtained primarily from zircon and used chiefly in ceramic and refractory compounds, as an alloying agent, and in nuclear reactors as a highly corrosion-resistant alloy. Atomic number 40; atomic weight 91.22; melting point 1,852°C; boiling point 4,377°C; specific gravity 6.56 (20°C); valence 2, 3, 4. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, Zr; atomic weight, 89.6. The metal contained in zirconia. It is commonly obtained in the form of a black powder, but is also known in the crystalline state, forming highly lustrous blackish-gray laminæ, having a specific gravity of 4.15. The amorphous metal takes fire when gently heated in the air, but the crystalline variety requires an intense heat for its ignition. The common acids do not attack it. Zirconium is a remarkable element in that it is very widely and generally diffused in nature, but nowhere, so far as is known, found in any one locality in large quantity; in this respect it has a decided resemblance to titanium. The form in which it occurs is that of the silicate (zircon), and usually in minute or even microscopic crystals, which have been detected in many granitic and syenitic rocks, as well as in various gneisses and crystalline schists. Zircon has been found also, but less abundantly, in some eruptive rocks, both ancient and modern. Zirconium is chemically most closely related to titanium, and both these metals have certain affinities with silicon, forming dioxids and volatile tetrachlorids, as does that non-metallic element.

Wiktionary

1. n. a metallic chemical element (symbol Zr) with an atomic number of 40.

GNU Webster's 1913

1. n. (Chem.) A rare element of the carbon-silicon group, intermediate between the metals and nonmetals, obtained from the mineral zircon as a dark sooty powder, or as a gray metallic crystalline substance. Symbol Zr. Atomic weight, 90.4.

WordNet 3.0

1. n. a lustrous grey strong metallic element resembling titanium; it is used in nuclear reactors as a neutron absorber; it occurs in baddeleyite but is obtained chiefly from zircon