The following morning, I found my mentor, Professor Annity, busily cleaning up after what looked like a series of curious experiments. As I entered the lab, she fixed me with a familiar sort of excited, faintly frenzied expression, and ushered me across to the workbench, upon which lay five similar-looking bundles, each slightly different in shape, each covered over with a cloth.

“Well! I may have worked all night, but... as you will learn, success comes with perseverance. Behold, my latest invention!” She gestured to the fifth bundle. “Ah! But before I unveil it, let us first examine failed experiments #1 - #4, the better for you to understand my processes.”

Fighting back my natural curiosity I nodded assent, and the good Professor indicated the first bundle. I peeked beneath the cloth. “This one, frankly, was a mistake... The second, well, as you can see - it’s even less interesting. Moving quickly on...” She picked up the third bundle and handed it to me. “This one is lighter than the others.” I nodded again - indeed, it did appear lighter. I replaced it on the bench. “So far, though - unremarkable. Experiment #4 though, I think you’ll agree, was an astonishing attempt!”

And indeed, dazzled though I was by the Professor’s ingenuity, as she made to lift the fifth veil and reveal her newest invention, I interrupted with a splutter. “Excuse me, Professor. I believe I may have deduced what it is you have created...”

What was the Professor's invention?

Hint 1:

The five taken together form, not a sequence, but a complete set.

  • $\begingroup$ Could we get a hint? $\endgroup$
    – Duck
    Sep 29, 2019 at 2:28
  • 4
    $\begingroup$ I had an idea that it would be the 5 words you can't say on television, but it turned out to be 7, so no. But the clue "Prof Annity" might help someone. $\endgroup$ Jan 27, 2020 at 23:32
  • $\begingroup$ Hmm... I got an idea! Professor Annity, Prof Annity, Profanity... That is it! I found a clue! (Sadly, only a partial). $\endgroup$ Feb 19, 2023 at 14:19

1 Answer 1


I think the Professor's Invention is a


Other inventions

#1 - "a mistake"


#2 - "even less interesting"


#3 - "lighter than the others"


#4 - "an astonishing attempt!"


So clearly the one that completes the set is


  • $\begingroup$ I have stared at this one for years and never been able to work this one out - great job! Can I ask what finally cracked it for you - what was the lightning bolt moment? $\endgroup$
    – Stiv
    Feb 20, 2023 at 9:41
  • 1
    $\begingroup$ @Stiv you know, it's funny, I hadn't looked at this in ages (but did many times after it was posted) but the answer below raised a flag in my inbox because I follow the question. So I decided to read it again and something about the hint suggested the pattern to me (group of five, not in sequence) so I looked up synonyms for "mistake" and tried to mess around with replacements there. Weirdly, the Prof Annity bit is probably what threw me off before but I think it's just a funny quirk rather than a clue. $\endgroup$
    – hexomino
    Feb 20, 2023 at 10:57

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