Q:

Are there words like "Percent", but for other quantities?

If "Percent" is based off of the pseudo-latin "per centum", then it stands to reason that one could use numbers such as ten (decum) or thousand (mīlle) to construct similar words as "perdec" or "permill".
Are there such words and would they be decipherable to the public?
Searching "perdec" gives a lot of hits for companies and foreign surnames, and "perdecage" gives a few people essentially expressing my same thought process.

A:

Yes there are
For example promile or per mille (‰) for 1/1,000th of something, which is used for describing water salinity and some other concentrations that need more precision.
I encountered in middle school geography class as part of standard school programme (the chapter/section/etc. on oceans), so I expect that yes, it should be recognisable. There are probably more obscure constructions that are less recognisable.

