also: クァルテット · クワルテット
quartet
Used in music for a group of four performers or a piece written for four parts. Also used metaphorically for any group of four.
from Italian quartetto
I went to hear a string quartet performance.
彼らはジャズカルテットを結成した。
They formed a jazz quartet.
They formed a jazz quartet back in college.
The piece was performed by a quartet.