ruby (Noun) — A transparent piece of ruby that has been cut and polished and is valued as a precious gem.
ruby (Noun) — A transparent deep red variety of corundum; used as a gemstone and in lasers.
ruby (Noun) — A deep and vivid red colour.
ruby (Noun) — (historical) a size of printing type.
ruby (Adjective) — Of a colour at the end of the colour spectrum (next to orange); resembling the colour of blood, cherries, tomatoes or rubies. ex. "The picture would come through dark with a ruby tinge"