An angel is generally a supernatural being found in various religions and mythologies. In Abrahamic religions and Zoroastrianism, angels are often depicted as benevolent celestial beings who act as intermediaries between God or Heaven and Humanity. Other roles of angels include protecting and guiding human beings, and carrying out God's tasks. Within Abrahamic religions, angels are often organized into hierarchies, although such rankings may vary between sects in each religion, and are given specific names or titles, such as Gabriel or "Destroying angel". The term "angel" has also been expanded to various notions of spirits or figures found in other religious traditions. The theological study of angels is known as "angelology". Angels who were expelled from Heaven are referred to as fallen angels.
The word angel in English is a blend of Old English engel (with a hard g) and Old French angele. Both derive from Late Latin angelus "messenger", which in turn was borrowed from Late Greek ἄγγελος aggelos, commonly transliterated by non-Greek speakers in its phonetic form ángelos. According to R. S. P. Beekes, ángelos itself may be "an Oriental loan, like ἄγγαρος ." The word's earliest form is Mycenaean a-ke-ro, attested in Linear B syllabic script.
The ángelos is the Septuagint's default translation of the Biblical Hebrew term mal’ākh, denoting simply "messenger" without specifying its nature. In the Latin Vulgate, the meaning becomes bifurcated: when mal’ākh or ángelos is supposed to denote a human messenger, words like nuntius or legatus are applied. If the word refers to some supernatural being, the word angelus appears. Such differentiation has been taken over by later vernacular translations of the Bible, early Christian and Jewish exegetes and eventually modern scholars.
In Zoroastrianism there are different angel-like figures. For example, each person has one guardian angel, called Fravashi. They patronize human beings and other creatures, and also manifest God's energy. The Amesha Spentas have often been regarded as angels, although there is no direct reference to them conveying messages, but are rather emanations of Ahura Mazda ("Wise Lord", God); they initially appeared in an abstract fashion and then later became personalized, associated with diverse aspects of the divine creation.
In the commentaries of Proclus (4th century, under Christian rule) on the Timaeus of Plato, Proclus uses the terminology of "angelic" (aggelikos) and "angel" (aggelos) in relation to metaphysical beings. According to Aristotle, just as there is a Prime Mover, so, too, must there be spiritual secondary movers.