Definition of stoma in US English:



  • 1Any 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
    • ‘The outer layer of the abaxial epidermis contains sunken stomata with strongly fluorescing chloroplasts in the guard cells.’
    • ‘Leaf stomata control plant CO 2 absorption through photosynthesis and water loss through transpiration.’
    • ‘However, the presence of both adaxial and abaxial stomata on leaves of T. pusillum var. texanum did differentiate it from other taxa in this species complex.’
    • ‘Until it is possible to be sure that the readings taken are not being influenced by fluctuations in the width of open stomata while the leaf is in the experimental cuvette, statistics on oxygen concentrations cannot be performed reliably.’
    • ‘The leaf pores, also called stomata, open to allow in carbon dioxide, which plants need for photosynthesis.’
    opening, orifice, aperture, hole, outlet, inlet, vent
    View synonyms
    1. 1.1Zoology A small mouthlike opening in some lower animals.
      • ‘Note the characteristic long and straight stoma of Rhabditidae, the well-developed teeth at the base of a short stoma of Diplogastridae, the well-sclerotized stoma lining in Panagrolaimidae and the stoma lining divided in several elements of Cephalobidae.’
    2. 1.2Medicine An artificial opening made into a hollow organ, especially one on the surface of the body leading to the gut or trachea.
      • ‘You have no speech at all and your airway is moved to a stoma in your neck.’
      • ‘A single lesion involving a tracheotomy stoma was treated with the direct application of the probe without using the bronchoscope.’
      • ‘An ileostomy with two openings includes an open stoma for effluent and another stoma for a mucous fistula.’
      • ‘Previously it has been due to cancer, however, this time it was because I had developed a very large hernia, which was causing great problems underneath my stoma (the opening created to replace my bowels).’
      • ‘One may speculate that the differences in rates of bleeding and infection can be explained by differences in the tracheostomy stoma following these two techniques.’


Late 17th century: modern Latin, from Greek stoma ‘mouth’.