The Quaternary period or the system of deposits laid down during it.
A quaternary compound.
Relating to or in number base four
Of fourth rank or order
Of a mathematical expression containing e.g. x⁴
quaternary ammonium
composed of four elements
Tetralogy of Fallot.
A group of four dramas, three tragic and one satiric, exhibited together at the festivals of Dionysus at Athens.
A combination of four symptoms.
A set of four works of art that are connected, and that can be seen either as a single work or as four individual works. They are commonly found in literature, film, or video games.