thrum          
 verb uk/θrʌm/ us/θrʌm/ -mm-
 [ I ]发出连续低沉的声音 
to make a continuous low sound
  The engine was thrumming steadily. 发动机稳稳地低声轰鸣。 
  [ T ](用吉他或其他弦乐器)弹出曲调,弹出节奏 
to play a guitar or similar stringed instrument in a way that makes a rhythm
  He can thrum a guitar, but he's not Jimmy Hendrix. 他会弹吉他,但不是吉米 · 亨德里克斯。 
 thrum       
noun [ S ] uk/θrʌm/ us/θrʌm/
 连续低沉的声音
a continuous low sound
  the steady thrum of horses galloping 马匹奔驰时发出的持续闷响