Noun
the length of breadth of a finger used as a linear measure
Source: WordNetOne of the sayings of Diogenes was that most men were within a finger's breadth of being mad; for if a man walked with his middle finger pointing out, folks would think him mad, but not so if it were his forefinger. Diogenes Laërtius
Most men are within a finger's breadth of being mad. Diogenes of Sinope