Other forms: rhyme schemes
In the lines of a poem, the pattern of words that sound alike is called a rhyme scheme. In a traditional ABAB rhyme scheme, the last word of every other line rhymes.
In songs or rhyming poetry, there are endless possible rhyme schemes. A couplet, a pair of lines that have the same meter and end in a similar sound, has one of the most simple rhyme schemes, often referred to as AA. The poet Shel Silverstein used this rhyme scheme to write "I have the measles and the mumps / A gash, a rash, and purple bumps."