You hear it a lot when referring to other idioms – so-and-so coined the phrase “cat’s pajamas” and such – but where did “coin the phrase” itself come from?
“To coin a phrase” means to invent a new phrase or, more commonly today, to precede a cliched or ironic phrase.
“So shall my Lungs Coine words till their decay.” -Shakespeare
The phrase “coining” refers, as you might imagine, to making coins by stamping metal with a die. The dies that stamped the metal were called coins and the “coined” money eventually took the word as their name.
”Coin” had many different spellings in the 16th century, including coyne, coign , coigne, and quoin.
In the 16th century “coining” also transferred to the subject of language. At the time, people often counterfeited coins and coining words meant creating false phrases, putting their own stamp on questionable word choices.
A good example of this comes from George Puttenham’s The arte of English poesie:
“Young schollers not halfe well studied…will seeme to coigne fine wordes out of the Latin.”
And one of the earliest uses of the exact term “coin a phrase” is found in the newspaper The Southport American in 1848:
“Had we to find…a name which should at once convey the enthusiasm of our feelings towards her, we would coin a phrase combining the extreme of admiration and horror and term her the Angel of Assassination.”
It seems the phrase has stuck around.