A fragment is a part of a larger work or a poem made to appear discontinuous or incomplete.

From A Poet’s Glossary

The following definition of the term fragment is reprinted from A Poet's Glossary by Edward Hirsch.

A part broken off, something cut or detached from the whole, something imperfect. Much of the work of the ancients comes down to us in fragments and tatters, cut pieces. As W. R. Johnson puts it in The Idea of Lyric (1982):

No experience in reading, perhaps, is more depressing and more frustrating than to open a volume of Sappho’s fragments and to rec­ognize, yet again—one always hopes that somehow this time it will be different—that this poetry is all but lost to us. . . . Even though we know that Greek lyric is mere fragments, indeed, because we know that Greek lyric is mere fragments, we act, speak, and write as if the unthinkable had not happened, as if pious bishops, careless monks, and hungry mice had not consigned Sappho and her lyrical colleagues to irremediable oblivion.

In the medieval and Renaissance eras, fragments were often allegorical, suggesting something broken off from a divine whole. They were survivals from an earlier era. Readers had become so accustomed to reading unfin­ished texts by the early nineteenth century that it became acceptable and even fashionable to publish poems that were intentionally fragmentary. The passion for ruins as well as the taste for poetic relics and antiquities contrib­uted to the acceptance of the romantic fragment, which we now recognize as a genre in its own right and a prototype of romantic poetry in general. One of Friedrich Schlegel’s fragments defines the genre: “A Fragment must as a miniature work of art be entirely isolated from the surrounding world and perfect in itself, like a hedgehog.” Coleridge’sKubla Khan: or a Vision in a Dream. A Fragment” (1816), Keats’s “Hyperion. A Fragment” (1818–1819), and Byron’s “The Giaour. A Fragment of a Turkish Tale” (1813) all were pre­sented as lyrics with a purposeful partiality. Anne Janowitz characterizes the romantic fragment as “a partial whole—either a remnant of something once complete and now broken or decayed, or the beginning of something that remains unaccomplished.” It becomes a radiant moment out of time, which can never be completed because it aspires to the infinite.

The modernist poets reinvented the fragment as an acutely self-con­scious mode of writing that breaks the flow of time, leaving gaps and tears, lacunae. They created discontinuous texts, collages and mosaics, fragmen­tary epics such as Ezra Pound’s The Cantos (1915–1969), Louis Zukofsky’s “A” (1927–1978), and T. S. Eliot’sThe Waste Land” (1922), which he sum­marizes as “These fragments I have shored against my ruins.” There is even greater vertigo in the destabilizing fragments of contemporary poetry, sometimes coolly giddy, as in John Ashbery, sometimes desperate for insight, as in Jorie Graham. In general, postmodernism is less regretful and nostal­gic than modernism—it no longer yearns for wholeness—and postmodern poets typically view the fragment as a kind of emancipation that breaks the omnipotence of totalizing systems. As a genre of disruption, the postmod­ern aesthetic of the fragment revels in its own incompleteness, its partial­ity, since all texts are incomplete and all poetic language insufficient. “The interruption of the incessant,” Maurice Blanchot writes, “that is the distin­guishing characteristic of fragmentary writing.” 

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