Merriam-Webster Collegiate Dictionary - muse

 I. verb  (~d; musing)  Etymology: Middle English, from Anglo-French ~r to gape, idle, ~, from Old French *mus mouth of an animal, from Medieval Latin musus  Date: 14th century  intransitive verb  1. to become absorbed in thought; especially to turn something over in the mind meditatively and often inconclusively  2. archaic wonder, marvel  transitive verb to think or say reflectively  Synonyms: see ponder  • ~r noun  II. noun  Date: 15th century a state of deep thought or dreamy abstraction  III. noun  Etymology: Middle English, from Middle French, from Latin Musa, from Greek Mousa  Date: 14th century  1. capitalized any of the nine sister goddesses in Greek mythology presiding over song and poetry and the arts and sciences  2. a source of inspiration; especially a guiding genius  3. poet