rhythm guitar       
noun [ U ] uk/ˈrɪð.əm ɡɪˌtɑːr/ us/ˈrɪð.əm ɡɪˌtɑːr/
 节奏吉他
a guitar part in a group that provides the rhythm of a piece of music, rather than the main tune which is played or sung by other musicians
  He plays rhythm guitar in a band.  他在一个乐队里弹节奏吉他。 
 The band now included Niki Sullivan on rhythm guitar. 现在乐队中包括了节奏吉他手尼基 · 沙利文。 
 - More examples
 - He has switched from drums to rhythm guitar.
 - It was a trio (lead guitar, rhythm guitar, and double bass).
 - If you ever want to see some great rhythm guitar, check out in "A Hard Day's Night" when they do "And I Love Her".
 - He became one of the best rhythm guitar players in the world.