'Stoma' definitions:

Definition of 'stoma'

noun

A minute epidermal pore in a leaf or stem through which gases and water vapor can pass [syn: stoma, stomate, pore]

noun

A mouth or mouthlike opening (especially one created by surgery on the surface of the body to create an opening to an internal organ)

From: GCIDE

Stoma \Sto"ma\, n.; pl. Stomata. [NL., fr. Gr. ?, ?, a mouth.]
1. (Anat.) One of the minute apertures between the cells in many serous membranes. [1913 Webster]
2. (Bot.) (a) The minute breathing pores of leaves or other organs opening into the intercellular spaces, and usually bordered by two contractile cells. (b) The line of dehiscence of the sporangium of a fern. It is usually marked by two transversely elongated cells. See Illust. of Sporangium. [1913 Webster]
3. (Zool.) A stigma. See Stigma, n., 6 (a) & (b) . [1913 Webster]