chuckle
Concise Oxford English Dictionary © 2008 Oxford University Press:
chuckle/ˈtʃʌkl/
▶verb laugh quietly or inwardly. ▶noun a quiet or suppressed laugh.
– derivatives
chuckler noun.
chuckler noun.
– origin C16: from chuck meaning ‘to cluck’ in ME.
'chuckle' also found in these Oxford entries:

