(butterflies)
1.
A ~ is an insect with large colourful wings and a thin body.
N-COUNT
2.
Butterfly is a swimming stroke which you do lying on your front, kicking your legs and bringing your arms over your head together.
N-UNCOUNT: also the N
3.
If you have butterflies in your stomach or have butterflies, you are very nervous or excited about something. (INFORMAL)
An exam, or even an exciting social event may produce butterflies in the stomach.
PHRASE