'In the swim' This expression, meaning "to be actively engaged or in the thick of things," comes from fishing, where a large group of fish in one location was sometimes called a "swim." Someone "in the swim," therefore, would be in the mainstream.
'In the nick of time' Up until the 1700s, both time and transactions were recorded by scoring notches or nicks on a stick called a tally. Even athletic events were scored this way, with a nick each time a team scored. When a last-minute score brought victory to a side, that mark was called "a nick, in time."
'In the groove' This expression, meaning "going smoothly," was first popular in the early days of American jazz. The allusion is to the quality of music produced when a needle runs firmly in the groove of a gramophone record. To musicians of the 1930s and 40s, music that was "in the groove" was pleasant. In the 1960s, the phrase gave rise to the word "groovy."
Linguist Robert Hendrickson cites an even earlier reference to "in the groove." He says the expression dates back to19th-century England, when it meant "stuck in a rut," like a cart stuck in a muddy groove. Hardly going smoothly.
To take someone 'down a peg' According to the most popular theory, this expression, meaning "to take conceit out of a braggart," comes from the British Navy. Lowering someone's worth is like lowering a ship's colors (or flags), which you would do on board by a system of pegs. The navy's custom was to raise colors in saluting a visiting dignitary - and the higher they were raised, the greater the honor. Naturally, to take the ship's colors down a peg would mean to decrease the honor - or a man's esteem.
Sources: Dictionary of Word Origins, by Jordan Almond; 'Loose Cannons and Red Herrings,' by Robert Claiborne; Encyclopedia of Word and Phrase Origins, by Robert Hendrickson; 'Why You Say It,' by Webb B. Garrison; Morris Dictionary of Word and Phrase Origins, by William Morris; Barnhart Dictionary of Etymology, by Robert K. Barnhart; and Brewer's Dictionary of Prose and Fable.
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