verb
-ters; -tered; -tering
of a bird or insect
to move or flap the wings quickly without flying [+ obj]
[no obj] :to fly lightly with quick beats of the wings
to move with quick, light movements [no obj]
[no obj] :to move or behave in a nervous and excited way
If your heart/stomach flutters, you become very nervous or excited.
noun
plural -ters
[count] :a quick, light movement
[singular] :a state of excitement or confusion
[count] Brit informal :a small bet
[noncount] technical :quick changes in the pitch of recorded sound