undercurrent vs tide

undercurrent and tide both are nouns.

Word	Noun	Adjective	Verb	Adverb
undercurrent	Yes	No	No	No
tide	Yes	No	Yes	No

undercurrent (noun)	tide (noun)
a subdued emotional quality underlying an utterance; implicit meaning	the periodic rise and fall of the sea level under the gravitational pull of the moon
a current below the surface of a fluid	something that may increase or decrease (like the tides of the sea)
	there are usually two high and two low tides each day