What does p.u. mean?

Factual Questions
1

Everyone says it when odorifious scents fill the air. Mention those 2 letters in a crowd and everyone’s nostrils do their little dance. But what does p.u. mean? Even Acronym Finder states it is not an acronym. It had to come from somewhere. Any ideas?

2

It’s “short” for phewwwwww!!!

3

This web page traces it back to Sanskrit:

http://hinduwebsite.com/general/sanskrit_english.htm

This one makes note of the PIE root *pu, meaning “rot, stink”
http://www.etymonline.com/p11etym.htm

This appears to be a very ancient word.

4

Try the Phrase Finder.