Ou(ch)

I was going very slowly down the stairwell of my house, especially slowly because I was carrying something bulky.  As a result, my left elbow was sticking outward, protruding  toward the wall.  When I was about halfway down, my elbow scraped against a pointed metal picture hanger, and it hurt like the dickens. 

As soon as the sharp metal object scraped against the skin on my elbow, I shouted "ow!", but then the momentum of my step carried me downward continuing to scrape against the picture hanger, and the "ow" became "owwwccchhhh!" 

The strange thing is that I was perfectly conscious that I was elongating the "ow" into "ow(ch)", and was slightly comforted by that enunciation of a word.  That is to say, the pain was somewhat alleviated by the fact that I was making a statement about what was happening to the skin and nerves on my elbow, rather than merely experiencing the pain and reacting to it with an automatic exclamation.

"Darn, that really smarts!!"

Etymology

Uncertain. Some sources say the interjection is attested since 1838 (and specifically in American English) and derives ultimately from German autsch, perhaps specifically via Pennsylvania German outch (“cry of pain”), as early attestations of the interjection are from Pennsylvania. However, others say the interjection is a "mere" or "natural" exclamation attested since the mid 1600s, and the 1933 OED cites one instance of a verb "ouch" in 1654, "Sancho Pancas Runs Ouching round the mountaine like a ranck-Asse".

(Wiktionary)

Selected readings

• "Ouch" (4/20/19)
• "The multivalence of interjections" (4/19/25) — Can AI learn to use interjections?