Here's a truly worthless word:(from poetry glossary)
A poem in a fixed form, consisting of a varying number of 4-line stanzas with lines rhyming alternately; the second and fourth lines of each stanza are repeated to form the first and third lines of the succeeding stanza, with the first and third lines of the first stanza forming the second and fourth of the last stanza, but in reverse order, so that the opening and closing lines of the poem are identical.
Sidelight: The pantoum is derived from the Malayan pantun, which follows the same rhyme and line patterns but differs in some other respects. In the pantun, which is traditionally improvised, the theme or meaning is conveyed in the second two lines of each quatrain, while the first two lines present an image or allusion which may or may not have an obvious connection with the theme.