Pronunciation: (mon'ad, mō'nad),[key] —n. 1. Biol. a. any simple, single-celled organism.
b. any of various small, flagellate, colorless ameboids with one to three flagella, esp. of the genus Monas. 2. Chem.an element, atom, or group having a valence of one. Cf. dyad (def. 3), triad (def. 2a).
3. Philos. a. (in the metaphysics of Leibniz) an unextended, indivisible, and indestructible entity that is the basic or ultimate constituent of the universe and a microcosm of it.
b. (in the philosophy of Giordano Bruno) a basic and irreducible metaphysical unit that is spatially and psychically individuated.
c. any basic metaphysical entity, esp. having an autonomous life.
4. a single unit or entity.