what's the word?

Stan (stainlessb), I have done a quick look the old-fashioned way, using a hard-copy dictionary.  Google Translate seems to give only limited possibilities.  According to the Cassell's French Dictionary, which I bought in the 1980s, here is what it says:
It appears that the hallmark meaning is more specific to the term "poinçon de contrôle" rather than a general use.  For philatelic terms, I think we should tag Xavier (hrdoktorx), as I think he will be able to give the best, most correct translation for your purposes.

Thank you!

JK, reming me what is "die" - I probably know the french term as I was raised in my late dad's printing/newspaper etc enterprise

René.....too lazy to do a search 

yes, the poincon is the engraved die (with no denomination, so it could be used multiple times). This would then be pressed into the plate (however many stamps were to be printed with each printing 'press".  These would be re-touched over time to adjust for wear or in the case of the Semeuse cameé to correct issues with the original poincon (engraved by Mouchon) that the Postmaster (and others I suppose) did not like. I am not sure why some variants only show up in specfic plate positions, whether it was something when the die was struck into the plate, or whether as a result of a 're touch"

I can only imagine the tedious task for those who got to go add the letters into the early GB QV plates i(Penny black, blue and red), but if not for that  some of the earliest stamps would be very difficult (or a much bigger task) to identify plate numbers. 

of course, much of this , while interesting does not aid me in identifying the different types

ammunition for academic discourse!!

Hi renden ,  apologies for my Scottish sense of humour with the joke reply above .    Here is the original "DIE" for the Penny Black 


redirect.viglink.com/?key=713b9e171d0c70c534903850e38fda93&subId=5386724&u=https%3A//ibb.co/HgBPqmw


The link stolen here from a post made by freid001 last year