Meaning

noun a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

noun a schwa that is incidental to the pronunciation of a consonant

noun an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves

originFrom Middle English murmur, murmor, murmour, from Old French murmure (modern French murmure), from Latin murmur (“murmur, humming, muttering, roaring, growling, rushing etc.”).

Etymology from Wiktionary, CC BY-SA 3.0