An extremely accurate reference clock whose operation is based on an atomic process, typically the frequency of electromagnetic radiation associated with a specified energy-level transition in an element such as cesium.

Alternative form of atomic bomb

A nuclear weapon.

(physics) The theory that all gross matter is composed of atoms. / (physics) Any of several theories that explain the structure of the atom, and of subatomic particles.

plural of atomic bomb

(rail transport) Acronym of Association Of Train Operating Companies.

(philosophy) The ancient Greek theory that all matter is composed of very small indestructible and indivisible particles.

Of or pertaining to atoms or to atomism. / Divided into separate elements; not holistic.

plural of atomic number

plural of atomic winter