Butterflies

any of numerous diurnal insects of the order Lepidoptera, characterized by clubbed antennae, a slender body, and large, broad, often conspicuously marked wings.
a person who flits aimlessly from one interest or group to another:
a social butterfly.
butterflies, (used with a plural verb) Informal. a queasy feeling, as from nervousness, excitement, etc.
a racing breaststroke, using a dolphin kick, in which the swimmer brings both arms out of the water in forward, circular motions.
Carpentry. butterfly wedge.
Sculpture. an X -shaped support attached to an armature.
one of the swinging brackets of a butterfly table.
Movies. a screen of scrim, gauze, or similar material, for diffusing light.
Cookery. to slit open and spread apart to resemble the spread wings of a butterfly.
Cookery. split open and spread apart to resemble a butterfly:
butterfly shrimp; butterfly steak.
Contemporary Examples

Pippa Joins Kate and William As They Mark Big Day at Friend’s Wedding Tom Sykes April 29, 2012
Warning: “Natural Medicine” Is Often Code for “Pseudoscience” Russell Saunders April 2, 2014
My Night at ‘America’s Got Talent’ With Mariann From Brooklyn Kevin Fallon July 30, 2013
The Stars Predict Your Week Starsky + Cox October 14, 2011
Last Hope for Costa Concordia’s Missing as Ship Tanks Risk Bursting Barbie Latza Nadeau January 19, 2012

Historical Examples

The Venetian School of Painting Evelyn March Phillipps
The Uncommercial Traveller Charles Dickens
Two Years in the Forbidden City The Princess Der Ling
My Double Life Sarah Bernhardt
Elements of Structural and Systematic Botany Douglas Houghton Campbell

plural noun
(informal) tremors in the stomach region due to nervousness
noun (pl) -flies
any diurnal insect of the order Lepidoptera that has a slender body with clubbed antennae and typically rests with the wings (which are often brightly coloured) closed over the back Compare moth related adjective lepidopteran
a person who never settles with one group, interest, or occupation for long
a swimming stroke in which the arms are plunged forward together in large circular movements
(commerce) the simultaneous purchase and sale of traded call options, at different exercise prices or with different expiry dates, on a stock exchange or commodity market
n.

The butterfly effect is a deceptively simple insight extracted from a complex modern field. As a low-profile assistant professor in MIT’s department of meteorology in 1961, [Edward] Lorenz created an early computer program to simulate weather. One day he changed one of a dozen numbers representing atmospheric conditions, from .506127 to .506. That tiny alteration utterly transformed his long-term forecast, a point Lorenz amplified in his 1972 paper, “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” [Peter Dizikes, “The Meaning of the Butterfly,” The Boston Globe, June 8, 2008]