From kluzo (to billow or dash over); a surge of the sea (literally or figuratively) -- raging, wave.
Thayer's Greek Lexicon
Strong's 2830: κλύδων
κλύδων, κλύδωνος, ὁ (κλύζω, to wash against); from Homer down; a dashing or surging wave, a surge, a violent agitation of the sea: τοῦὕδατος, Luke 8:24; τῆςθαλάσσης, James 1:6 (Jonah 1:4, 12; Wis. 14:5). [SYNONYMS:κλύδων, κῦμα: κῦμαa wave, suggesting uninterrupted succession; κλύδωνa billow, surge, suggesting size and extension. So too in the figurative application of the words. Schmidt, chapter 56.]
Luke 8:24 - N-DMS GRK:καὶ τῷ κλύδωνι τοῦ ὕδατος NAS: the wind and the surging waves, and they stopped, KJV: and the raging of the water: INT: and the raging of the water
James 1:6 - N-DMS GRK:διακρινόμενος ἔοικεν κλύδωνι θαλάσσης ἀνεμιζομένῳ NAS: is like the surf of the sea, KJV: is like a wave of the sea INT: doubts is like a wave of [the] sea being driven by the wind