thrum1

 
Pronunciation: /θrʌm/

verb (thrums, thrumming, thrummed)

[no object]
  • make a continuous rhythmic humming sound: the boat’s huge engines thrummed in his ears
  • [with object] strum (the strings of a musical instrument) in a rhythmic way: he thrums the strings [no object]: blind men thrum and hum in the soft air

noun

[usually in singular]
  • a continuous rhythmic humming sound: the steady thrum of rain on the windows

Origin:

late 16th century (as a verb): imitative