reduplicative

/rɪˈduːplɪkətɪv/
adjective
  1. Relating to or involving repetition or doubling, especially of a word or syllable.
    • Linguists study reduplicative forms like 'tick-tock' and 'chit-chat'.
    • The poem used a reduplicative structure to emphasize the rhythm.
    • The reduplicative pattern in 'bye-bye' is common in baby talk.