1.(Min.) A precious stone of a carmine red color, sometimes verging to violet, or intermediate between carmine and hyacinth red. It is a red crystallized variety of corundum. Note: Besides the true or Oriental ruby above defined, there are the balas ruby, or ruby spinel, a red variety of spinel, and the rock ruby, a red variety of garnet. "Of rubies, sapphires, and pearles white."
2.The color of a ruby; carmine red; a red tint. "The natural ruby of your cheeks."
3.That which has the color of the ruby, as red wine. Hence, a red blain or carbuncle.
5.(Zool.) Any species of South American humming birds of the genus Clytolaema. The males have a ruby-colored throat or breast.
...