Final answer:
Emily Dickinson repeats the word 'greedy' to emphasize the overwhelming and all-consuming force of the wave that took the boat away, conveying the intensity of nature's power.
Step-by-step explanation:
In the second stanza of "Unreturning" by Emily Dickinson, the poet most likely repeats the word greedy to emphasize the insatiable nature of the wave and its overwhelming force. This repetition creates an image of the wave greedily taking away the boat from the shore, suggesting it is inevitable and all-consuming. The repetition is meant to highlight the intensity and destructiveness of the natural force, personifying the wave with a human-like desire that knows no bounds or considerations for what it takes, underlining the helplessness of the "little craft" against such a powerful force.