(simile, uncommon) With absolute regularity and precision; faultlessly.

(physics, chemistry, dated) Pedantic form of mass number. Symbol: A.

(physics) a hydrogen-like system consisting of an ordinary nucleus with a hadron in orbit.

(physics, chemistry) the equivalent of an atom in which either the nucleus, or an electron, is replaced by some other subatomic particle

(physics, chemistry) Any atom which has a single valence electron in a shell well outside any other electrons in the aton; approximates the hydrogen atom.

Alternative form of atomic bomb

plural of Rydberg atom

plural of atom bomb

(philosophy) The doctrine that the world consists of ultimate logical "facts" (or "atoms") that cannot be broken down any further.

(informal) A particle accelerator.