IPA: //kwɔːrˈtɛt//
KK: /kwɔrˈtɛt/
A group of four people or things, often used in music to refer to four singers or musicians performing together.
The string quartet played beautifully at the concert.
Quartet → It is formed from "quartus" (meaning fourth) and the suffix "-et" (a diminutive suffix used to indicate a smaller version or group). The word "quartet" refers to a group of four musicians or singers, hence a smaller group of four.
Think of the word 'fourth' ('quartus') to remember that a 'quartet' is a group of four.