2. (Philos. of Leibnitz) 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.
3. (Zo["o]l.) One of the smallest flangellate Infusoria;
esp., the species of the genus Monas, and allied genera.
4. (Biol.) A simple, minute organism; a primary cell, germ,
or plastid.
5. (Chem.) An atom or radical whose valence is one, or which
can combine with, be replaced by, or exchanged for, one
atom of hydrogen.
{Monad deme} (Biol.), in tectology, a unit of the first order
of individuality.