reduplication (act of increasing something to double what it was before); repetition (act or instance of repeating or being repeated); reduplication (morphological process in which the root or stem of a word, part of that, or the whole word is repeated exactly or with a slight change)
to double, to reduplicate, to double down (to increase something to double what it was before); to repeat (to do or say again (and again)); to reduplicate (to repeat a word or part of a word in order to form a new word or phrase, possibly with modification of one of the repetitions)