in philosophy, a particle of matter, so minute as to admit of no division. Atoms are the minima nature, and are conceived as the first principles or component parts of all physical magnitude. See CHEMISTRY.

ATOMICAL philosophy, or the doctrine of atoms, a system which, from the hypothesis that atoms are endowed with gravity and motion, accounted for the origin and formation of things. This philosophy was first broached by Moebius, some time before the Trojan war; but was much cultivated and improved by Epicurus, whence it is denominated the Epicurean philosophy. See EPICUREAN.