re sirrah.
It's very common in Shakespeare, where, as you say, it was used by nobles to speak to inferiors.
I have never heard the word. I've never spoken to a "noble" and probably never will!
Ah! But the point is, has a noble ever spoken
to you, believing you are his inferior?
I actually have seen (never heard) the word sirrah, but then again, I've read a lot of Shakespeare's plays. Ah, being an English major...
Lapin, on the other hand...I suspected it must have something to do with rabbits, but I didn't know what. I doubt if it's a common word in America.