gallium

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A rare metallic element that is liquid near room temperature, expands on solidifying, and is found as a trace element in coal, bauxite, and other minerals. It is used in semiconductor technology and as a component of various low-melting alloys. Atomic number 31; atomic weight 69.72; melting point 29.78°C; boiling point 2,403°C; specific gravity 5.907; valence 2, 3. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, Ga; specific gravity, 5.935. A rare malleable metal, discovered by means of spectrum analysis in 1875 by M. Lecoq de Boisbaudran in the zinc-blende of Pierrefitte in the Pyrenees. It is of a grayish-white color and brilliant luster, and fuses at so low a point (30° C. or 86° F.) as to melt readily by the mere warmth of the hand. It has as yet been prepared only in small quantities. In its properties it is related to aluminium, and its spectrum consists of two violet lines, one well defined and eminently characteristic.
2. n. The discovery of this chemical element was peculiarly interesting, as furnishing striking evidence of the soundness of the theoretical views, as to the relations of the elements, which led Mendeléjeff in 1869 to predict the existence of such a substance and give a description of the properties it would be found to exhibit: his prediction required scarcely any correction when the element was actually discovered.

Wiktionary

1. n. A chemical element (symbol Ga) with an atomic number of 31; a soft bluish metal.

GNU Webster's 1913

1. n. (Chem.) A rare metallic element, found combined in certain zinc ores. It is white, hard, and malleable, resembling aluminium, and remarkable for its low melting point (86° F., 30° C.). Symbol, Ga; at. wt., 69.9. Gallium is chiefly trivalent, resembling aluminium and indium. It was predicted with most of its properties, under the name eka-aluminium, by the Russian chemist Mendelyeev on the basis of the periodic law. This prediction was verified in its discovery (in 1875) by the French chemist Lecoq de Boisbaudran by its characteristic spectrum (two violet lines), in an examination of a zinc blende from the Pyrenees.

WordNet 3.0

1. n. a rare silvery (usually trivalent) metallic element; brittle at low temperatures but liquid above room temperature; occurs in trace amounts in bauxite and zinc ores