very thin, as thin as a hair
A fishing line made from hair.
The line along one's forehead where hair starts growing.
A very thin line in writing, drawing, or typography.
A very thin fissure.
Dirty or untidy.
Infested with lice.
Unwell; under the weather.
Remarkably bad; of poor quality.
Underhanded; mean; contemptible.
Filled or packed (with something, usually bad).