(Non-english questioner) To countersink means to drill a sloped hole so that screw heads can sink into the material to be hidden.
In German for example the term for this action is "senken", which would translate to only "sink" (not "countersink", which would literally translate to German "gegensenken" - which doesn't make any sense in German).
I know the followng meanings of "counter":
- a "mechanism" to increase numbers
- something like "opposite" or "reverse" (like in "counterattack")
- the furniture in a shop or bar where the salesperson works
None of them makes sense for screws. What exactly does "counter" mean here?