A small aperture is a very small opening, usually used to control the flow of air or light. The term can be used to describe four different objects: a PINHOLE (7 letters), a STOMA (5 letters), an ostiole (7 letters), and a mousehole (9 letters). A PINHOLE is a tiny hole made in a thin material, such as paper or metal. A STOMA is a natural opening in a plant or animal, such as the opening of a leaf or the mouth of an insect. An ostiole is a small opening in a fungus, such as a mushroom. Finally, a mousehole is a small hole made by a mouse to enter and exit a building.