Racecar.

Was it a car or a cat I saw?

No lemons, no melon.

A man, a plan, a canal, Panama.

What is so special about the sentences above? That's right...  They are so-called palindromes since they read the same backwards as forwards. These examples are at letter level.

A palindrome can have an odd number of letters and the middle letter acts as pivot, like the /e/ in racecar. Wouldn't pirouette words be a rather cool name for them? Palindromes can also have an even number of letters: in that case to equal parts mirror one another. Sometimes these parts do not constitute full words, sometimes they do. In Dutch that would be words like NEKKEN: it is a palindrome and it is formed by concatenating two existing mirror words : NEK en KEN.

Non-existent but why not... KOORTSSTROOK, KOTSSTOK (that's the finger in your mouth to vomit). Maybe this has already been researched.. but my feeling is that English phonotaxis is less apt to make such words than Dutch. If any language tech student is reading this and looking for a research topic I think this might be interesting. Oh... btw... I think I found one that would sound kind of cool in English: if ever trams are made to drive autonomously we could call them...  SMARTTRAMS ,-) That would actually make a lot of sense for bidirectional trams where the front can be the back and the back can be the front... indeed... just like a palindrome!

It could be interesting to see across languages eg whether a given language with it morphology and phonotactic constraints is more or less apt for palindrome construction than another one for instance.