Final answer:
The poetic form of 'O Captain! My Captain!' is an elegy that mourns the death of President Abraham Lincoln.
Step-by-step explanation:
The poetic form of "O Captain! My Captain!" is an elegy.
An elegy is a type of poem that mourns the loss of a person or commemorates their life. In this case, the poem is about the death of President Abraham Lincoln and is written by American poet Walt Whitman.
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