croon

 
Pronunciation: /kruːn/

verb

[no object]
  • hum or sing in a soft, low voice, especially in a sentimental manner: she was crooning to the child [with object]: the female vocalist crooned smoky blues into the microphone
  • [with direct speech] say in a soft, low voice: ‘Goodbye, you lovely darling,’ she crooned

noun

[in singular]
  • a soft, low voice or tone: he sang in a gentle, highly expressive croon

Origin:

late 15th century (originally Scots and northern English): from Middle Low German and Middle Dutch krōnen 'groan, lament'. The use of croon in standard English was probably popularized by Robert Burns