but ‧ ter ‧ fly /ˈbʌtəflaɪ $ -ər-/ BrE AmE noun ( plural butterflies ) [countable]
[ Language: Old English ; Origin: buterfleoge , from butere ( ⇨ ↑ butter 1 ) + fleoge 'fly' ; perhaps because many types of butterfly are yellow, or because people believed that butterflies steal milk and butter ]
1 . a type of insect that has large wings, often with beautiful colours
2 . have/get butterflies (in your stomach) informal to feel very nervous before doing something:
I always get butterflies before an exam.
3 . the butterfly a way of swimming by lying on your front and moving your arms together over your head while your legs move up and down
4 . someone who usually moves on quickly from one activity or person to the next:
Gwen’s a real social butterfly.