'To run a foil' definitions:

Definition of 'To run a foil'

From: GCIDE

Foil \Foil\, n.
1. Failure of success when on the point of attainment; defeat; frustration; miscarriage. --Milton. [1913 Webster]
Nor e'er was fate so near a foil. --Dryden. [1913 Webster]
2. A blunt weapon used in fencing, resembling a smallsword in the main, but usually lighter and having a button at the point. [1913 Webster]
Blunt as the fencer's foils, which hit, but hurt not. --Shak. [1913 Webster]
Isocrates contended with a foil against Demosthenes with a word. --Mitford. [1913 Webster]
3. The track or trail of an animal. [1913 Webster]
To run a foil,to lead astray; to puzzle; -- alluding to the habits of some animals of running back over the same track to mislead their pursuers. --Brewer. [1913 Webster]