whimpering
Concise Oxford English Dictionary © 2008 Oxford University Press:
whimper/ˈwɪmpə(r)/
▶verb make a series of low, feeble sounds expressive of fear, pain, or discontent. ▶noun a whimpering sound.
– derivatives
whimperer noun,
whimpering noun,
whimperingly adverb.
whimperer noun,
whimpering noun,
whimperingly adverb.
– origin C16: from dial. whimp ‘to whimper’, of imitative origin.
'whimpering' also found in these Oxford entries:

