As a verb, to muse is to consider something thoughtfully. As a noun, it means a person — especially a woman — who is a source of artistic inspiration.
In mythology, the Muses were nine goddesses who symbolized the arts and sciences. Today, a muse is a person who serves as an artist's inspiration. Often filmmakers talk about a certain actor being a muse — meaning the actor inspired a movie. Writers, painters, musicians, and other artists have muses. Muse can also refer to thinking deeply. If you muse about something, you're giving it serious thought. You can't muse in five seconds. People muse on certain ideas for years.