The confusable verbs clench and clinch are close not only in spelling but in etymology. In fact, Bryan Garner notes in Garner’s Modern American Usage, 3rd Edition, that, historically, clench and clinch were one word with two spellings that underwent differentiation.
So how do you know whether you’re clenching or clinching?
In general, clench is a physical act and clinch is a figurative one — except when it isn’t.
Clenching involves tightening one’s muscles — either holding something tightly (such as a steering wheel) or setting or closing tightly (like fists or your jaw). You might clench your teeth in anger, or you might clench a cigar (or, as in the picture, a stick) in your teeth; either way, keeping in mind the Es in clench and teeth might help lead you to the right spelling.
Unfortunately, associating muscles with clenching won’t always lead you true, because there is an exception. Keep reading.
In general usage, to clinch means to settle or make irrefutable (as an argument) or to secure or win (as an election or World Series title). Associating the in in win with the in in clinch can help you remember.
However, because English vocabulary is never easy, clinch also has special uses in woodworking and boxing.
In woodworking, If you drive a nail through some boards so that the sharp end of the nail pokes all the way through, you clinch that nail by hammering the protruding end so that it bends back into the wood. Both this type of fastening and the part of the nail that is thus turned back go by the noun clinch as well.
It’s a common tactic during a boxing match for one fighter to wrap his or her arms around the other fighter to slow the pace of the round or to prevent the opponent from getting in a punch at full speed. You’d think this might be called clenching because it involves holding something tightly, but in boxing jargon, this is called clinching. This sort of tactical hug is called a clinch, and two boxers thus engaged are “in a clinch.”
Logical? No, but English usage rarely is. Just like boxing.