To make a rapid series of short, hard sounds, or to disturb or unnerve someone.
Middle English, probably imitative of the sound. Related to Dutch 'ratelen' and German 'rasseln'. The figurative sense of disturbing someone emerged from the idea of shaking something up, literally and metaphorically.
Rattles are among humanity's oldest toys and musical instruments, found in archaeological sites worldwide - there's something primal about the appeal of contained chaos, the satisfaction of controlling random noise. The word perfectly captures how certain sounds can simultaneously delight children and absolutely rattle adults' nerves.
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