purring
Concise Oxford English Dictionary © 2008 Oxford University Press:
purr/pɜː(r)/
▶verb
- 1 (of a cat) make a low continuous vibratory sound expressing contentment.
- 2 (of a vehicle or engine) move or run smoothly while making a similar sound.
– origin C17: imitative.
'purring' also found in these Oxford entries:

