- a variety of chalcedony having straight parallel bands of alternating colors.
- (not used technically) an unbanded chalcedony dyed for ornamental purposes.
- black, especially a pure or jet black: The pelt of this animal can range from onyx to light brown, depending on the season.
- a nail of a finger or toe.
- made of or set with banded chalcedony: He wore the onyx cufflinks she had given him for his birthday.
- black, especially jet black: She was a vision in black, from her onyx hair to her shiny boots.
- a variety of chalcedony with alternating black and white parallel bands, used as a gemstone. Formula: SiO 2
- a compact variety of calcite used as an ornamental stone; onyx marble. Formula: CaCO 3
