Why is the circuit board abreviation for transistor "Q"?
There are claims that, after initial chaos, eventually the letter Q was chosen because of the popular TO18/TO39 case styles.



Just look at it from the bottom:



And of course, 'T' had been used for transformers since decades earlier.

Now, finding trustworthy sources available on the web... well, it hasn't been a lucky few minutes for me, but I know I read this somewhere in print years ago.