Final answer:
The poetic form of 'O Captain! My Captain!' is an elegy. It mourns the loss of President Abraham Lincoln.
Step-by-step explanation:
The poetic form of 'O Captain! My Captain!' is an elegy. An elegy is a poem that mourns the loss or death of someone, usually a prominent figure or a loved one. In this case, the poem is written by Walt Whitman as a tribute to President Abraham Lincoln after his assassination.
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