The Muses Greek mythology, poetry and literature, are the goddesses of the inspiration of literature, science and the arts. They were considered the source of the knowledge, related orally for centuries in the ancient culture that was contained in poetic lyrics and myths.
|The Nine Muses: Clio, Thalia, Erato, Euterpe, Polyhymnia, Calliope, Terpsichore, Urania, Melpomene|
The muses are said to be the daughters of Zues, also called Nymphs at times. Some authors invoke Muses when writing poetry, hymns or epic history. The invocation typically occurs at or near the beginning, and calls for help or inspiration, or simply invites the Muse to sing through the author.
Muse can also be used to describe a) a guiding spirit or b) a source of inspiration. They are most often associated with works of poetry, or epic literature.
If you are using the term Muse to describe your hunky young cover model that can't string sentences together, please stop. Especially if said "Muse" came about AFTER the work of fiction was written. There is also no such thing as musing, or I mused this.