A very thin fissure.
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.
very thin, as thin as a hair
A blacksmith's fuller or chisel, having a square shank for insertion into a square hole in an anvil, called the hardy hole.
Anything, especially a plant, that is hardy.
Impudent.
Having rugged physical strength; inured to fatigue or hardships.
Able to survive adverse growing conditions.
Brave and resolute.