Procrastinating at work, I researched "Sinus" and apparently it is latin with two potential meanings:
sinus: curve, fold, bend /pocket, lap /bay, gulf.
sinus: inner feeling, secret heart.
So those sound right, it is overstable and will bend, and maybe it gives you an "inner feeling" if you are into that kind of thing
The disc has a latin phrase on it:
"is mos non sinus obvious ventus"
I used google to translate it from the latin and I got:
"it will not allow the obvious favorite"
but there are variations, particularly "ventus" could mean wind, and sinus turn, so I think it really means something like:
"it will not turn in heavy wind"
Good use of an overstable driver.