What’s the catch is an idiom that dates to the 1800s. An idiom is a word, group of words or phrase, or phrasal verbs that have a figurative meaning that is not easily deduced from its literal definition. These figures of speech or literary devices often use descriptive imagery; common idioms are words and phrases used in the English language in order to convey a concise idea, and are often colloquialisms or descriptors that are spoken or are considered informal or conversational. An idiom may be a euphemism, an understatement or exaggeration, or an expression of irony or hyperbole. English idioms can illustrate emotion more quickly than a phrase or expression 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 or other parts of speech is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions that native speakers understand such as in a blue moon, spill the beans, let the cat out of the bag, chin up, eye to eye, barking up the wrong tree, bite the bullet, red herring, hit the nail on the head, kick the bucket, blow off steam, jump on the bandwagon, piece of cake, hit the sack, and raining cats and dogs, as they attempt to translate them word for word, which yields only the literal meaning. 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. It is possible to memorize a list of idioms, but it may be easier to pay attention to the use of idioms in everyday speech, where peculiar imagery will tell you that the expressions should not be taken literally. We will examine the meaning of the idiomatic phrase what’s the catch?, where it came from, and some examples of its use in sentences.
The phrase what’s the catch? is a retort when one believes that an offer is too good to be true. One may ask what’s the catch? if he believes that a situation or deal is being presented on its best face and that problems or drawbacks are being hidden. For instance, if a stranger approaches you and hands you a hundred dollar bill, you may wonder what you will have to do to repay that stranger, or if the money is stolen. In this case you may respond, “What’s the catch?” The word catch, in this case, means a hidden cost or a hidden trap. The idiom what’s the catch? came into use in the 1850s and is associated with P. T. Barnum, a flamboyant American showman who is associated with hucksterism and skirting the truth.
So the U.S. Court of Appeals for the 11th Circuit ruled it was unconstitutional to force felons to pay all their financial obligations before allowing them to register to vote, but what’s the catch? (The Tampa Bay Times)
After a big snowfall, roads in Chugiak-Eagle River are cleared faster and cheaper than those in Anchorage. So what’s the catch? (The Chugiak-Eagle River Star)
Given that Google is all about the data, by which I mean your data, what’s the catch? (Forbes Magazine)