Boron

a nonmetallic element occurring naturally only in combination, as in borax or boric acid, and obtained in either an amorphous or a crystalline form when reduced from its compounds. Symbol: B; atomic weight: 10.811; atomic number: 5.
Historical Examples

A Textbook of Assaying: For the Use of Those Connected with Mines. Cornelius Beringer and John Jacob Beringer
The Scarlet Lake Mystery Harold Leland Goodwin
Scientific American Supplement, No. 841, February 13, 1892 Various
Inorganic Plant Poisons and Stimulants Winifred E. Brenchley
The White Spark Orville Livingston Leach
Inorganic Plant Poisons and Stimulants Winifred E. Brenchley
A Textbook of Assaying: For the Use of Those Connected with Mines. Cornelius Beringer and John Jacob Beringer
Inorganic Plant Poisons and Stimulants Winifred E. Brenchley
An Elementary Study of Chemistry William McPherson
Inorganic Plant Poisons and Stimulants Winifred E. Brenchley

noun
a very hard almost colourless crystalline metalloid element that in impure form exists as a brown amorphous powder. It occurs principally in borax and is used in hardening steel. The naturally occurring isotope boron-10 is used in nuclear control rods and neutron detection instruments. Symbol: B; atomic no: 5; atomic wt: 10.81; valency: 3; relative density: 2.34 (crystalline), 2.37 (amorphous); melting pt: 2092°C; boiling pt: 4002°C
n.
boron
(bôr’ŏn’)
Symbol B
A shiny, brittle, black metalloid element extracted chiefly from borax. It is a good electrical conductor at high temperatures and a poor conductor at low temperatures. Boron is necessary for the growth of land plants and is used in the preparation of soaps, abrasives, and hard alloys. It is also used in the control rods of nuclear reactors as a neutron absorber. Atomic number 5; atomic weight 10.811; melting point 2,300°C; sublimation point 2,550°C; specific gravity (crystal) 2.34; valence 3. See Periodic Table.