A murmur is a soft, low, continuous sound that's hard to hear clearly. When a class full of students talks quietly while working, their voices blend into a gentle murmur. When a brook flows over smooth stones, it makes a peaceful murmur. The word captures sounds that are present but not loud or distinct.

When used as a verb, to murmur means to speak in this quiet, indistinct way. You might murmur a quick “excuse me” as you squeeze past someone, or murmur comfort to a frightened pet. People often murmur when they don't want to disturb others or when they're speaking privately.

The word also has an important medical meaning. Doctors listen for heart murmurs, which are unusual sounds blood makes as it flows through the heart. Many heart murmurs are harmless, just like the quiet, continuous sound the word describes. A doctor uses a stethoscope to detect these murmurs during a checkup.

Notice how murmur sounds like what it means: soft m's and r's that roll gently off your tongue, never sharp or loud. Whether it's voices, water, or the human heart, a murmur is always something subtle and ongoing rather than sudden or jarring.