From Longman Dictionary of Contemporary Englishbutterflybut‧ter‧fly /ˈbʌtəflaɪ $ -ər-/ ●●○ noun (plural butterflies) [countable] 1 
HBIa type of insect that has large wings, often with beautiful colours2 → have/get butterflies (in your stomach)3 → the butterfly4 CHANGE YOUR MINDsomeone who usually moves on quickly from one activity or person to the next Gwen’s a real social butterfly.
HBIa type of insect that has large wings, often with beautiful colours2 → have/get butterflies (in your stomach)3 → the butterfly4 CHANGE YOUR MINDsomeone who usually moves on quickly from one activity or person to the next Gwen’s a real social butterfly.Examples from the Corpus
butterfly• These people can take many blows, but I, I am fragile as a butterfly.• The snails had vanished, but now some one seemingly had traced a picture of a butterfly in the dirt.• A butterfly wing has a dynamically changing structure that allows myriad responses to its own induced wing vortices.• I feel a kind of reverence in late summer when I visit that abandoned butterfly garden.• He collected rocks and butterflies and devoured accounts of recent scientific expeditions.• At about the seventeenth day the first butterflies will probably start to emerge.• For the patterned butterflies I used a small part of the leaf design.• Gwen's a real social butterfly.• I shut my eyes and tried to see the butterfly.Origin butterfly Old English buterfleoge, from butere ( → BUTTER1) + fleoge “fly”; perhaps because many types of butterfly are yellow, or because people believed that butterflies steal milk and butter 