On the fly

On the fly is an idiom that seems to have originated in the United States. An idiom is a word, group of words or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms are words and phrases used in the English language in order to convey a concise idea, and are often spoken or are considered informal or conversational. English idioms can illustrate emotion more quickly than a phrase that has a literal meaning, even when the etymology or origin of the idiomatic expression is lost. An idiom is a metaphorical figure of speech, and it is understood that it is not a use of literal language. Figures of speech have definitions and connotations that go beyond the literal meaning of the words. Mastery of the turn of phrase of an idiom, which may use slang words, or other parts of speech is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions such as in a blue moon, spill the beans, let the cat out of the bag, in the same boat, bite the bullet, barking up the wrong tree, kick the bucket, hit the nail on the head, face the music, under the weather, piece of cake, when pigs fly, and raining cats and dogs, as they attempt to translate them word for word, which yields only the literal meaning. English phrases that are idioms should not be taken literally. In addition to learning vocabulary and grammar, one must understand the phrasing of the figurative language of idiomatic phrases in order to know English like a native speaker. We will examine the meaning of the idiom on the fly, where it may have come from, and some examples of its use in sentences.

On the fly means to do something spontaneously, to solve problems as they come up, to adapt to an ever-changing environment. To do something on the fly means to do something without thought, one simply reacts to the situation as problems are presented. The expression on the fly most probably originated with American baseball and came into use in the mid-1800s. A fly in American baseball is a ball that is hit by the batter into the air, without the ball touching the ground.


Whether the effects are obvious or more subtle, the coronavirus pandemic has made an impact on every facet of life, business and culture, forcing institutions to adapt on the fly. (The Bulletin)

Mobile test sites make adjustments on the fly (The Examiner Enterprise)

Illinois adjusts on the fly to meet medical supply needs in a coronavirus ‘Wild West’ (The Chicago Sun Times)

Many teachers improvise, counting on patience from parents and students as they transition to online learning on the fly. (USA Today)

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