Webster's Revised Unabridged Dictionary · 1913

Vap

Vap (vap) , noun

[See Vapid.]

That which is vapid, insipid, or lifeless; especially, the lifeless part of liquor or wine. [Obsolete]
In vain it is to wash a goblet, if you mean to put into it nothing but the dead lees and vap of wine. — Jer. Taylor