Numen, pl. numina, is a Latin term for "divinity", or a "divine presence", "divine will" (etymologically, the word means "a nod of the head", here referring to a deity as it were "nodding", or making its will or its presence known). Numen was also used in the imperial cult of ancient Rome, to refer to the guardian-spirit, 'godhead' or divine power of a living emperor—in other words, a means of worshiping a living emperor without literally calling him a god.
Numen is also used by sociologists to refer to the idea of magical power residing in an object, particularly when writing about ideas in the western tradition. When used in this sense, numen is nearly synonymous with mana. However, some authors reserve use of mana for ideas about magic from Polynesia and southeast Asia.
The literal meaning is simply "a nod", or more accurately, for it is a passive formation, "that which is produced by nodding", just as flamen is "that which is produced by blowing", i.e., a gust of wind. It came to mean "the product or expression of power" — not, be it noted, power itself.
Thus, numen (divinity) is not personified (although it can be a personal attribute) and should be distinguished from deus (god).
The supposition that a numious presence in the natural world supposed in the earliest layers of Italic religion, as it were an "animistic" element left over in historical Roman religion and especially in the etymology of Latin theonyms, has often been popularly implied, but was criticised as "mostly a scholarly fiction" by McGeough (2004).
The cult of Augustus was promoted by Tiberius, who dedicated the Ara Numinis Augusti. In this context, a distinction can be made between the terms numen and genius.
The phrase "numen eris caeloque redux mirabere regna" appears on line 129 of the poem Metrum in Genesin, attributed to Hilary of Arles.
Cicero uses the term to signify the "active power" of a Roman god.Virgil uses the plural form of numen in the Aeneid: magna numina precari, translated as "prayed to the great gods." By simulacra numinum the historian Tacitus refers to the "statues of the active powers."Pliny the younger speaks of the numen historiae to mean the divine power of history.Lucretius uses the expression numen mentis, or "bidding of the mind."
The expression Numen inest appears in Ovid's Fasti (III, 296) and has been translated as 'There is a spirit here'. Its interpretation, and in particular the exact sense of numen has been discussed extensively in the literature.
In modern times, the term (referring to the Christian God) has been used in various expressions:
Innocue vivito, numen adest (Live blameless; God is here.) was the motto of Linnaeus, taken from Ovid's Ars Amatoria (I, 640).
^Kevin McGeough The Romans: new perspectives 2004:179 "Numinous Forces and Other scholarly Inventions"; "Scholars may have to content themselves with nodes of meanings for the Italic gods rather than hard-and-fast definitions," observes Charles Robert Phillips III, in "A Note on Vergil's Aeneid 5, 744," Hermes104.2 (1976:247–249) p. 248, with recent bibliography; Gerhard Radke's classification of the forms and significances of these multifarious names in Die Götter Altitaliens (Münster, 1965) was criticized as "unwarranted precision" in the review by A. Drummond in The Classical Review, New Series, 21.2 (June 1971:239–241); the coupling and uncoupling of Latin and Italic cognomina of the gods, creating the appearance of a multitude of deities, were classically dissected in Jesse Benedictus Carter, De Deorum Romanorum Cognominibus: Quaestiones Selectae (Leipzig, 1898).
^Fishwick, Duncan (July 1969). "Genius and Numen". Harvard Theological Review62 (3): 356–367. doi:10.1017/s0017816000032405. Reprinted in Fishwick, D. (1990).
^Fishwick, Duncan (May 1970). "'Numina Augustorum". The Classical Quarterly (New Series)20 (1): 191–197. doi:10.1017/s0009838800044773. Reprinted in Fishwick, D. (1990).