A "pinhole" is a very tiny hole, like the size of a pin. It is usually used to refer to a small opening in an object, such as a camera, that lets in light. Full definition
If you can't get your hands on eclipse glasses, you're not S.O.L. Channel your inner Pinterest mom and make pinhole cameras with your kids. (mommyish.com)
The left side of the watch houses a small pinhole microphone for voice actions and making calls, while a small speaker grille sits on the right for all sorts of sound output. (androidcentral.com)
During the course of her artistic career she has done extensive exploration of pinhole photography. (artthrob.co.za)