Like the limerick, the double dactyl has a fixed structure and is usually humorous, but is considerably more rigid and difficult to write. There must be two stanzas, each comprising three lines of dactylic dimeter ( ¯ ˘ ˘ ¯ ˘ ˘ ) followed by a line consisting of just a choriamb ( ¯ ˘ ˘ ¯ ). The two stanzas have to rhyme on their last lines. The first line of the first stanza is repetitive nonsense. The second line of the first stanza is the subject of the poem, which is supposed to be a double-dactylic proper noun (though Hecht and other poets sometimes bent or ignored this rule). There is also a requirement for at least one line, preferably the antepenultimate line of the second stanza, to be entirely one double dactyl word. Some purists still follow Hecht and Pascal's original rule that no single six-syllable word, once used in a double dactyl, should ever be knowingly used again.
A self-referential example by Roger L. Robison:
An example by John Hollander:
A similar verse form called a McWhirtle was invented in 1989 by American poet Bruce Newling. Another related form is the double amphibrach, similar to the McWhirtle but with stricter rules more closely resembling the double dactyl.
- The first published collection of double dactyls was Jiggery-Pokery: A Compendium of Double Dactyls, edited by Anthony Hecht and John Hollander. Many of the poems had previously appeared in Esquire starting in 1966.
- John Bellairs' classic fantasy novel The Face in the Frost (1969) contains several double dactyls, used as nonsense magic spells.
- The first published collection of double dactyls by a single author was Centicore Poems, [Series] I; being, A Non-canonical Collection of Entirely Prejudiced Double Dactyls "perpetrated by Jay Dillon" (Ann Arbor, Michigan: Dactylomaniac Press, 1972), OCLC (Worldcat) no. 498258515. Only one copy of this book is known to survive, in the British Library (London), General Reference Collection shelfmark X.902/1639.
- Abbreviated Lays is a 2003 collection of double dactyl poetry about Roman history.
- Anthony Hecht and John Hollander, eds. Jiggery-Pokery, A Compendium of Double Dactyls (New York: Atheneum, 1967)
- Reyes, A.T. (poems), Edgar, S.S.O. (notes) and Herrmann, C. (drawings) (2003), Abbreviated lays: stories of ancient Rome, from Aeneas to Pope Gregory I, in double-dactylic rhyme, Oxford: Oxbow Books, ISBN 1842171119 Catalyst Library