- In wood, a small, round hole made by a beetle or worm in the standing timber.
- In plaster, a surface defect caused by trapped air.
- In painted surfaces, a defect usually caused by impurities or dirt.
- In glazed ceramic surfaces, a small round hole.
- A tiny hole or puncture. For instance, the aperture of certain optical devices or systems. 2. A pinhole (1) resulting from a defect or fault. For example, that formed in a metal during electroplating.