stoma vs water stoma

stoma and water stoma both are nouns.

Word	Noun	Adjective	Verb	Adverb
stoma	Yes	No	No	No
water stoma	Yes	No	No	No

As nouns, water stoma is a hyponym of stoma; that is, water stoma is a word with a more specific, narrower meaning than stoma:

stoma: a minute epidermal pore in a leaf or stem through which gases and water vapor can pass
water stoma: a pore that exudes water on the surface or margin of a leaf of higher plants

Other hyponyms of stoma include germ pore, hydathode, water pore, lenticel.

stoma (noun)	water stoma (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)	a pore that exudes water on the surface or margin of a leaf of higher plants
a minute epidermal pore in a leaf or stem through which gases and water vapor can pass