"Epizeuxis"

From Wikipedia

In rhetoric, an epizeuxis is the repetition of a word or phrase in immediate succession, typically within the same sentence, for vehemence or emphasis.

From the OED

Etymology: modern Latin, < Greek ἐπίζευξις a fastening upon, < ἐπιζευγνύναι, < ἐπί upon + ζευγνύναι to yoke

Rhetoric.

  A figure by which a word is repeated with vehemence or emphasis.

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