In Neoplatonic thought: any of the indivisible metaphysical entities (‘units’) which serve to mediate between the absolutely transcendent unity of the One, from which the universe emanates, and the multiplicity of things in the universe. Also occasionally: a Platonic form or idea.
The idea of henads is particularly associated with Proclus (a.d. 410–85), who conceived of them as also constituting an order of divine beings.
Late 17th century; earliest use found in Theophilus Gale (1628–1679), ejected minister and theologian. From ancient Greek ἑνάδ-, ἑνάς unit from ἕν, neuter corresponding to εἷς (masculine) one + -άς.