Monad
Webster's Dictionary [1]
(1): ( n.) A simple, minute organism; a primary cell, germ, or plastid.
(2): ( n.) An ultimate atom, or simple, unextended point; something ultimate and indivisible.
(3): ( n.) The elementary and indestructible units which were conceived of as endowed with the power to produce all the changes they undergo, and thus determine all physical and spiritual phenomena.
(4): ( n.) One of the smallest flangellate Infusoria; esp., the species of the genus Monas, and allied genera.
(5): ( n.) An atom or radical whose valence is one, or which can combine with, be replaced by, or exchanged for, one atom of hydrogen.
The Nuttall Encyclopedia [2]
The name given by Leibnitz to one of the active simple elementary substances, the plurality of which in their combinations or combined activities constitutes in his regard the universe both spiritual and physical; it denotes in biology an elementary organism.
