Whitman’s unusual stanza form uses the following rhyme scheme: AABBCDED. Though this scheme repeats in each of the poem’s three stanzas, the rhymes vary greatly in terms of exactness. Many rhymes are perfectly matched. In fact, the D rhymes in all three stanzas are exact: “red,” “head,” and “tread” (lines 6, 14, and 22) are all made to rhyme with “dead” (lines 8, 16, and 24). Yet Whitman also frequently uses slant rhymes, which are imperfect rhymes that typically share the same consonants but have different vowels. As an example, consider the first half of the second stanza (lines 9–12):

     O Captain! my Captain! rise up and hear the bells;
     Rise up—for you the flag is flung—for you the bugle trills,
     For you bouquets and ribbon’d wreaths—for you the shores
a-crowding,
     For you they call, the swaying mass, their eager faces
turning

All four end rhymes in these lines are slant. The words “bells” and “trills” almost match, save for their different vowels. Even less perfect is the rhyme formed between “a-crowding” and “turning,” which only share their unstressed final syllable: “-ing.” This type of rhyme, which doesn’t fall on the line’s final stressed syllable, is known as a feminine rhyme. Whitman also uses this form of rhyme in the first stanza’s pairing of “exulting” and “daring” (lines 3 and 4). These subdued forms of rhyme bring a linguistic flair that isn’t too ostentatious, thus matching the high-minded seriousness of Whitman’s subject.