Angel, a general term denoting a subordinate superhuman being in monotheistic religions, e.g.. Islam, Judaism, Christianity, and in allied religions, such as Zoroastrianism. In polytheism the grades of superhuman beings are continuous; but in monotheism there is a sharp distinction of kind, as well as degree, between God on the one hand, and all other superhuman beings on the other; the latter are the "angels."
"Angel" is a transcription of the Gr. ἄγγελος, messenger. ἄγγελος in the New Testament, and the corresponding mal'akh in the Old Testament, sometimes mean "messenger," and sometimes "angel," and this double sense is duly represented in the English Versions. "Angel" is also used in the English Version for אביר 'Abbir, Ps. lxxviii. 25. (lit. "mighty"), for אלהים 'Elohim, Ps. viii. 5, and for the obscure שנאן shin'an, in Ps. lxviii. 17.
In the later development of the religion of Israel, 'Elohim is almost entirely reserved for the one true God; but in earlier times 'Elohim (gods), bnē 'Elohim, bnē Elim (sons of gods, i.e. members of the class of divine beings) were general terms for superhuman beings. Hence they came to be used collectively of superhuman beings, distinct from Yahweh, and therefore inferior, and ultimately subordinate. So, too, the angels are styled "holy ones," and "watchers," and are spoken of as the "host of heaven" or of "Yahweh." The "hosts," צבאות Sebaoth in the title Yahweh Sebaoth, Lord of Hosts, were probably at one time identified with the angels. The New Testament often speaks of "spirits," πνεύματα.  In the earlier periods of the religion of Israel, the doctrine of monotheism had not been formally stated, so that the idea of "angel" in the modern sense does not occur, but we find the Mal'akh Yahweh, Angel of the Lord, or Mal'akh Elohim, Angel of God. The Mal'akh Yahweh is an appearance or manifestation of Yahweh in the form of a man, and the term Mal'akh Yahweh is used interchangeably with Yahweh (cf. Exod. iii. 2, with iii. 4; xiii. 21 with xiv. 19). Those who see the Mal'akh Yahweh say they have seen God. The Mal'akh Yahweh (or Elohim) appears to Abraham, Hagar, Moses, Gideon, etc., and leads the Israelites in the Pillar of Cloud. The phrase Mal'akh Yahweh may have been originally a courtly circumlocution for the Divine King; but it readily became a means of avoiding crude anthropomorphism, and later on, when the angels were classified, the Mal'akh Yahweh came to mean an angel of distinguished rank. The identification of the Mal'akh Yahweh with the Logos, or Second Person of the Trinity, is not indicated by the references in the Old Testament; but the idea of a Being partly identified with God, and yet in some sense distinct from Him, illustrates the tendency of religious thought to distinguish persons within the unity of the Godhead, and foreshadows the doctrine of the Trinity, at any rate in some slight degree.
In the earlier literature the Mal'akh Yahweh or Elohim is almost the only mal'akh ("angel") mentioned. There are, however, a few passages which speak of subordinate superhuman beings other than the Mal'akh Yahweh or Elohim. There are the cherubim who guard Eden. In Gen. xviii., xix. (J) the appearance of Yahweh to Abraham and Lot is connected with three, afterwards two, men or messengers; but possibly in the original form of the story Yahweh appeared alone. At Bethel, Jacob sees the angels of God on the ladder, and later on they appear to him at Mahanaim. In all these cases the angels, like the Mal'akh Yahweh, are connected with or represent a theophany. Similarly the "man" who wrestles with Jacob at Peniel is identified with God. In Isaiah vi. the seraphim, superhuman beings with six wings, appear as the attendants of Yahweh. Thus the pre-exilic literature, as we now have it, has little to say about angels or about superhuman beings other than Yahweh and manifestations of Yahweh; the pre-exilic prophets hardly mention angels. Nevertheless we may well suppose that the popular religion of ancient Israel had much to say of superhuman beings other than Yahweh, but that the inspired writers have mostly suppressed references to them as unedifying.
Moreover such beings were not strictly angels.
The doctrine of monotheism was formally expressed in the period immediately before and during the Exile, in Deuteronomy and Isaiah; and at the same time we find angels prominent in Ezekiel who, as a prophet of the Exile, may have been influenced by the hierarchy of supernatural beings in the Babylonian religion, and perhaps even by the angelology of Zoroastrianism. Ezekiel gives elaborate descriptions of cherubim; and in one of his visions he sees seven angels execute the judgment of God upon Jerusalem. As in Genesis they are styled "men," mal'akh for "angel" does not occur in Ezekiel. Somewhat later, in the visions of Zechariah, angels play a great part; they are sometimes spoken of as "men," sometimes as mal'akh, and the Mal'akh Yahweh seems to hold a certain primacy among them. Satan also appears to prosecute (so to speak) the High Priest before the divine tribunal. Similarly in Job the bne Elohim, sons of God, appear as attendants of God, and amongst them Satan, still in his rôle of public prosecutor, the defendant being Job. Occasional references to "angels" occur in the Psalter; they appear as ministers of God.
In Ps. lxxviii. 49 the "evil angels" of A. V. conveys a false impression; it should be "angels of evil," as R. V., i.e. angels who inflict chastisement as ministers of God.
The seven angels of Ezekiel may be compared with the seven eyes of Yahweh in Zech. iii. 9, iv. 10. The latter have been connected by Ewald and others with the later doctrine of seven chief angels, parallel to and influenced by the Ameshaspentas (Amesha Spenta), or seven great spirits of the Persian mythology, but the connexion is doubtful.