Relax

The word relax has its origins in the Proto-Indo-European (PIE) root sleg (to be slack, to be languid). I can just hear some of the ancient peoples, “I had a really sleg day a work” or “Hey, slegger, get your butt in gear!” or “Give me a bit of sleg, willya?”
 
From PIE sleg comes Latin laxus (loose; not to be confused with lexis) and laxare (to loosen). Latin re- (back, again, once more) + laxare = relaxare (to relax, to loosen, open, stretch out); e.g., to stretch out on the couch.
 
The verb ‘to relax’ (to make something less compact or dense) comes to English in the late 14th century from Old French relaschier (to set free, to soften, to reduce) from Latin relaxare.
 
Relax meaning to decrease tension is from the early 15th century. Relax meaning to become less formal is from 1837. Relax meaning to become less tense is from 1935.
 
So, what are we to make of the word exlax? Latin ex = from, out of, without, former. Ex + lax. “Yesterday, I was relaxed but, today, after the stresses of work, I am feeling very exlaxed.” Does exlax mean that I am ‘out of lax’? Hmmm…
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
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