sto·ma / ˈstōmə/ • n. (pl. sto·mas or sto·ma·ta / -mətə; ˌstōˈmätə/ ) Bot. any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width that allows movement of gases in and out of the intercellular spaces. Also called stomate. ∎  Zool. a small mouthlike opening in some lower animals. ∎  Med. an artificial opening made into a hollow organ, esp. one on the surface of the body leading to the gut or trachea.DERIVATIVES: sto·mal adj. ( Med. ).

stoma (pl. stomata) In botany, pore found mostly on the undersides of leaves that allow atmospheric gases to pass in and out for respiration and photosynthesis. Surrounding each stoma are two guard cells that can close to prevent excessive loss of water vapour. See also gas exchange; transpiration

stoma (stoh-mă) n. (pl. stomata)
1. (in anatomy) the mouth or any mouthlike part.

2. (in surgery) the artificial opening of a tube that has been brought to the abdominal surface (see colostomy, ileostomy). s. therapist a nurse specially trained in the care of these openings and the appliances used with them.
—stomal adj.

stoma (pl. stomata) A pore, large numbers of which are present in the epidermis of leaves (especially on the undersurface) and young shoots. Stomata function in gas exchange between the plant and the atmosphere. Each stoma is bordered by two semicircular guard cells, whose movements (due to changes in water content) control the size of the aperture. The term stoma is also used to mean both the pore and its associated guard cells.

stoma (pl. stomata) A small opening, many of which are found in the epidermal layers of plants, allowing access for carbon dioxide and egress for water. Stomata are surrounded by guard cells which control the pore size.