What is "supernaculum"

Supernaculum \Su`per*nac"u*lum\, adv. & n. [NL., from L. super over + G. nagel, a nail, as of the finger, or a corruption of L. super and ungulam claw.]

1. A kind of mock Latin term intended to mean, upon the nail; -- used formerly by topers.
   --Nares.

   Drinking super nagulum [supernaculum], a device of drinking, new come out of France, which is, after a man hath turned up the bottom of the cup, to drop it on his nail and make a pearl with that is left; which if it slide, and he can not make it stand on by reason there is too much, he must drink again for his penance.
   --Nash.

2. Good liquor, of which not enough is left to wet one's nail.
   --Grose.

adv. (context obsolete English) According to the rules of an old drinking game in which the drinker upturned the empty cup and had to drink more if the remaining droplets spilled beyond the edge of his fingernail.