(1):
(n.) Native alumina or aluminium sesquioxide, Al2O3; corundum; esp., the blue transparent variety of corundum, highly prized as a gem.
(2):
(n.) The color of the gem; bright blue.
(3):
(a.) Of or resembling sapphire; sapphirine; blue.
(4):
(n.) Any humming bird of the genus Hylocharis, native of South America. The throat and breast are usually bright blue.