Democritus(noun)

Greek philosopher who developed an atomistic theory of matter (460-370 BC)

Democritus(ProperNoun)

A Greek philosopher (c.460-c.370 BC). The originator of the atomic theory together with his teacher Leucippus.

Democritus

a Greek philosopher, born in Abdera, Thrace, of wealthy parents; spent his patrimony in travel, gathered knowledge from far and near, and gave the fruits of it in a series of writings to his contemporary compatriots, only fragments of which remain, though they must have come down comparatively entire to Cicero's time, who compares them for splendour and music of eloquence to Plato's; his philosophy was called the Atomic, as he traced the universe to its ultimate roots in combinations of atoms, in quality the same but in quantity different, and referred all life and sensation to movements in them, while he regarded quiescence as the summum bonum; he has been called the Laughing Philosopher from, it is alleged, his habit of laughing at the follies of mankind; b. 460 B.C.