Repetition refers to the use of the same word or phrase multiple times and is a fundamental poetic technique.
From A Poet’s Glossary
The following additional definition of the term repetition is reprinted from A Poet's Glossary by Edward Hirsch.
Repetition—the use of the same term several times—is one of the crucial elements in poetry. “Repetition in word and phrase and in idea is the very essence of poetry,” Theodore Roethke writes in “Some Remarks on Rhythm” (1960). It is one of the most marked features of all poetry, oral and written, one of the primary ways we distinguish poetry itself. Repetition, as in rhyme, is a strong mnemonic device. Oral poets especially use it for remembering structures. The incantatory magic of poetry—think of spells and chants, of children’s rhymes and lullabies—has something to do with recurrence, with things coming back to us in time, sometimes in the same way, sometimes differently. Repetition is the primary way of creating a pattern through rhythm. Meaning accrues through repetition. One of the deep fundamentals of poetry is the recurrence of sounds, syllables, words, phrases, lines, and stanzas. Repetition can be one of the most intoxicating features of poetry. It creates expectations, which can be fulfilled or frustrated. It can create a sense of boredom and complacency, but it can also incite enchantment and inspire bliss.
Many of the sound devices of poetry (alliteration, assonance, consonance) depend on recurrence. Metrical patterns are established by recurrences, and so are poetic forms (the canzone, the sestina), some with repetends and refrains. The repeating structure of the catalog is one of the legacies of the Hebrew Bible to later poets, and some of the key devices of free verse (anaphora, parallelism) are structures of repetition. One could be forgiven for thinking that our brains are hardwired for repetition. Peter Sacks writes in The English Elegy (1987), “Repetition creates a sense of continuity, of an unbroken pattern such as one may oppose to the extreme discontinuity of death.”
Repetition can be so insistent that it spills over into obsessiveness, as in the defiant title of Daniel Hoffman’s book Poe Poe Poe Poe Poe Poe Poe (1972), which borrows its signal rhythm from Edgar Allan Poe’s poem “The Bells” (1849). Poe uses different kinds of repetition (internal and end rhyme, meter, words, lines) to create a hypnotic effect. He concludes with a man in a belfry dancing, yelling and
Keeping time, time, time,
In a sort of Runic rhyme,
To the Pæan of the bells —
Of the bells: —
Keeping time, time, time,
In a sort of Runic rhyme,
To the throbbing of the bells —
Of the bells, bells, bells —
To the sobbing of the bells: —
Keeping time, time, time,
As he knells, knells, knells,
In a happy Runic rhyme,
To the rolling of the bells —
Of the bells, bells, bells: —
To the tolling of the bells —
Of the bells, bells, bells, bells,
Bells, bells, bells —
To the moaning and the groaning of the bells.