It's just a receding hairline -- it's not like you're going bald.
There was a hairline crack in the airplane's wing.
In the horrendous crash at the end of Stage 1, Tyler Hamilton sustained two hairline fractures in his right collarbone.
A close, careful visual check in good light may reveal the tiny hairline cracks spreading out like a spider-web over the tire walls.
A long handled hammer was all that was needed to detect wheels with hairline fractures.
In men however the patern of loss usually starts with a receding hairline which then advances to thin the top of the head.
Sight through the rear sight and the window in the mirror and align the hairline at the reflection of the face of the compass.