tidal current vs aegir

tidal current and aegir both are nouns.

Word	Noun	Adjective	Verb	Adverb
tidal current	Yes	No	No	No
aegir	Yes	No	No	No

As nouns, aegir is a hyponym of tidal current; that is, aegir is a word with a more specific, narrower meaning than tidal current:

tidal current: the water current caused by the tides
aegir: a high wave (often dangerous) caused by tidal flow (as by colliding tidal currents or in a narrow estuary)

Other hyponyms of tidal current include bore, eager, eagre, tidal bore.

tidal current (noun)	aegir (noun)
the water current caused by the tides	a high wave (often dangerous) caused by tidal flow (as by colliding tidal currents or in a narrow estuary)