<u>Rhyme</u> is the <u>repetition</u> of the last syllable at the end of a line, which is used to create a harmonious sound in a piece of poetry.
The words <em>"knot"</em> and <em>"plot"</em> rhyme because their ending <em>"ot"</em> has a <u>homophonous</u> sound, adding a pleasant effect to the poem.