1. A tiny opening in human skin, or in the skin or other outer covering of an animal, through which substances can pass: Perspiration, for example, is released through the pores in the human body.
2. A tiny opening in a leaf or stem of a plant: Pores are used in plants to absorb or release substances, such as in photosynthesis or respiration.
3. A small space that is surrounded by rock or soil: Pores in rocks may be filled with water, crude oil, or natural gas.
4. Etymology: from Latin porus "a pore" (a small opening or empty space); which came from Greek poros, "a pore", literally, "a passage, a way [through]".

Although the ancient Greeks could examine the skin only with their eyes, and possibly with the aide of a primitive lens, they clearly recognized the presence of pores, or passageways, through which sweat was excreted.

A cavity inside a material that is impermeable when the material is immersed in a liquid: Closed pores can be contrasted to open pores, or the spaces between particles, cracks, and capillaries that extend into materials from their surfaces.

Impermeable refers to a situation that does not permit the passage of liquid, gas, or other fluids to take place.

One of the external openings of taste buds on the tongue: The reason why little Susy could enjoy her ice cream so much was because of the many taste pores allowing dissolved ice cream (or food) to come in contact with the taste receptors.