(physics) the study of the interaction of electromagnetic radiation with electrically charged matter within the framework of relativity and quantum mechanics

(quantum mechanics) Any of a class of solids (such as that of helium) whose atoms or molecules undergo large zero-point motion even in the quantum ground state (at absolute zero).

(physics) A predicted state of matter, containing deconfined quarks and gluons, present in the very early universe (first millionth of a second), and recreated at extremely high energy densities, such as those in the collision of heavy atomic nuclei as speeds very close to the speed of light.

(quantum mechanics) The quantum theory of the gravitational field. / (quantum mechanics) The study of quantum fields in curved spacetime.

(mathematics) a polynomial equation of the second degree.

(simile) To appear to be exactly what one is.

A dance originating in the mid-1700s with four couples forming a square, rather much like the modern square dance. / The music for this dance.

(intransitive) To dance the quadrille.

Quadrille ruled graph paper, quad paper.

A square tiling of the plane.