aquatic vs subaquatic

aquatic is a noun but subaquatic is not a noun.

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

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

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