Exploring the Meaning of Kuma in Greek

κῦμα describes “a wave,” appearing in narratives of peril at sea and in one vivid line of moral imagery. In the Gospels and Acts it belongs to scenes where water’s motion threatens a vessel; in Jude it becomes a picture drawn from the sea’s unruly surface.

Occurrences

“Behold, a violent storm came up on the sea, so much that the boat was covered with the waves, but he was asleep.” (Matthew 8:24)

Here κῦμα belongs to a “violent storm” on the sea and is tied to the boat’s immediate danger: it is “covered with the waves.” The wording places the waves not as distant scenery but as an active force that overtakes the vessel. In the same sentence, the contrast is sharp between the overwhelming motion outside (“covered”) and the calm inside the boat (“he was asleep”), so κῦμα helps set the crisis level of the moment.

“But the boat was now in the middle of the sea, distressed by the waves, for the wind was contrary.” (Matthew 14:24)

In this account κῦμα is connected to prolonged strain rather than sudden swamping. The boat is “in the middle of the sea,” and its condition is described as “distressed by the waves.” The explanation that “the wind was contrary” frames the waves as the sea’s response to opposing wind; κῦμα marks the churning surface that makes forward progress difficult and produces continuing pressure on the boat.

“A big wind storm arose, and the waves beat into the boat, so much that the boat was already filled.” (Mark 4:37)

Mark’s phrasing gives κῦμα a strikingly physical role: the waves “beat into the boat.” The motion is not merely surrounding the vessel but striking it and entering it. The result clause—“so much that the boat was already filled”—shows κῦμα as a mechanism of flooding. The word thus serves the narrative by turning the storm into measurable danger: the boat’s capacity is being overcome by what the waves drive inside.

“But coming to a place where two seas met, they ran the vessel aground. The bow struck and remained immovable, but the stern began to break up by the violence of the waves.” (Acts 27:41)

In Acts κῦμα appears within a detailed description of a shipwreck. The vessel reaches “a place where two seas met,” runs aground, and becomes fixed at the front: “The bow struck and remained immovable.” Against that immovable bow, the stern is exposed to repeated impact, and κῦμα is the immediate agent of destruction: it breaks up “by the violence of the waves.” The verse’s structure makes the waves’ “violence” the reason the ship’s rear cannot hold together, highlighting wave-action as a battering force when the ship can no longer maneuver.

“wild waves of the sea, foaming out their own shame; wandering stars, for whom the blackness of darkness has been reserved forever.” (Jude 1:13)

Jude uses κῦμα as part of an image: “wild waves of the sea.” The waves are characterized as untamed and turbulent, and their motion is pictured as producing visible froth—“foaming out their own shame.” Within the line’s tightly packed metaphors, κῦμα supplies the sense of restless, uncontrolled surge on the sea’s surface, now applied to describe a shame that spills out as conspicuously as foam.

Sense and Usage

Across these passages κῦμα consistently stays within the concrete domain of the sea’s moving surface, but the scenes show several facets of what waves do. In Matthew 8:24 the waves are large enough and forceful enough to cover a boat; κῦμα is associated with being overwhelmed. In Matthew 14:24 the waves distress a boat that is already far from shore, presenting the ongoing hardship of rough water rather than a single moment of inundation. Mark 4:37 intensifies the same maritime danger by describing waves that strike and enter the vessel, so κῦμα becomes a direct cause of the boat filling. Acts 27:41 places waves at the climactic end of a voyage, where the ship’s loss of mobility turns wave impact into structural failure; κῦμα is explicitly linked with “violence” and the breaking up of the stern.

Within these narrative uses, κῦμα serves as more than a neutral description of the sea. Each context pairs the waves with another element—storm, contrary wind, grounding—and κῦμα names the part of the threat that is felt at the hull and seen in the immediate environment around the boat. The word marks what turns wind and weather into contact: the waves cover, distress, beat into, and batter. Even without shifting away from its basic referent, κῦμα therefore helps depict degrees of peril: from surface agitation that strains a vessel, to overtopping that threatens to swamp it, to repeated pounding that breaks it apart.

Jude 1:13 shows how κῦμα can be taken from its literal setting and pressed into figurative description. The phrase “wild waves of the sea” does not move the word’s reference away from waves; rather, it draws on their observable behavior—unruliness and foaming—to paint a moral portrait. The added detail “foaming out their own shame” depends on what waves visibly do at their crest and crash: they throw up froth. κῦμα thus carries a ready-made picture of motion that is uncontrolled and outwardly expressive, making it apt for a comparison where inner corruption becomes outward display.

Imagery

In these verses κῦμα repeatedly evokes the boundary between human craft and a powerful sea. Boats and ships appear as the vulnerable human element—covered, distressed, filled, grounded—while waves are the immediate shape of the danger pressing in. Jude’s “wild waves of the sea, foaming out their own shame” draws from the same sensory world: the churning surface that will not stay still and the foam that cannot be hidden, turning maritime turbulence into a compact, memorable image.

Sources: Lexical data from Strong’s Exhaustive Concordance and the Translators Brief Lexicon of Extended Strongs for Greek (STEPBible, CC BY). Occurrence data from the Translators Amalgamated Greek New Testament (STEPBible, CC BY). Scripture quotations from the World English Bible (public domain).