subaquatic vs aquatic

subaquatic is not a noun while aquatic is a noun.

Word	Noun	Adjective	Verb	Adverb
subaquatic	No	Yes	No	No
aquatic	Yes	Yes	No	No

subaquatic (noun)	aquatic (noun)
	a plant that lives in or on water

subaquatic (adjective)	aquatic (adjective)
partially aquatic; living or growing partly on land and partly in water	operating or living or growing in water
growing or remaining under water	relating to or consisting of or being in water