Varied in metre. The term is applied to verse forms and stanzas or strophes in which lines of different lengths are found, usually arranged in a consistent order of variation and rhyming pattern (although verse in open form is also by definition heterometric, as are some unrhymed forms including the haiku). Some kinds of poem, such as the limerick, the clerihew, and the standard form of the ballad, are expected to be heterometric; and variation in line length is often found in the ode. Certain stanza forms, including the Burns stanza, the Spenserian stanza, and the quatrain in common measure or short measure, display heterometric patterns. The opposite kind of poem or stanza in unvaried metre is called isometric. Noun: heterometry.