Crooning a tune is a form of singing that is characterized by a smooth, gentle, and melodic sound. It is often associated with popular music from the 1920s and 1930s, as well as jazz and blues. The term 'CROON' comes from the Old English word 'CRONE, ' which means to hum or murmur. To CROON a tune is to sing it in a soft, gentle, and melodic way. It is a style of singing that is often used to express emotion and create a romantic atmosphere.