Idiom is defined as “a speech form or an expression of a given language that is peculiar to itself grammatically or cannot be understood from the individual meanings of its elements, as in keep tabs on.” Other terms for idiom, depending on the application, are jargon or colloquial expression or slang.
The writer’s primary objective is to communicate to the reader. Writers often like to ‘spice up’ a passage by inserting some slang expressions or industry-specific jargon, or colloquial expressions to make their writing more entertaining and lively. One disadvantage in doing this is the 'spiced up' expressions might not be understood by a variety of readers, or might undesirably date the writer and make the writing untrustworthy to a part of the reading audience.
The most important thing a writer can do is anticipate the general reading audience of the piece and conduct careful research to determine what idioms are familiar to the audience the writing targets. Younger people especially may be offended by inadequate attempts by older writers to mimic their slang. And remember: A little goes a long way. Don’t over-spice your writing with too much colloquial expression or lingo, or it will become unreadable. Also a choice phrase can quickly become overused and will stand out as a tired cliché in your writing. (See the last line of the last paragraph below for a shining example.)
Some common older idioms like “get your goat,” “beat around the bush,” “burn the midnight oil,” “chow down,” “it’s a cinch,” “elbow grease,” “count your chickens before they hatch,” “green” or “wet behind the ears,” “down pat,” “nose to the grindstone,” “pay the piper,” “fair to midland,” and “with bells on,” may have lost their relevance. Some slang idioms like “tubular,” and “sock it to me” that were popular in the past have lost their zest or meaning. Also simple words or phrases like “fat,” “cool,” and “hot” as slang may actually mean something new the writer is not aware of. Keeping abreast of current lingo and taking special care in researching can help relieve the idiocy of idioms and make your writing sing like a bird.
Gwynn E. Ambrose
The Cat’s Fancy