Clutter

google

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late Middle English: variant of dialect clotter ‘to clot’, influenced by cluster and clatter.

wiktionary

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From Middle English cloteren(“to form clots; coagulate; heap on”), from clot(“clot”), equivalent to clot +‎ -er(frequentative suffix). Compare Welsh cludair(“heap, pile”), cludeirio(“to heap”).

etymonline

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clutter (v.)

1550s, "to collect in heaps, crowd together in disorder," variant of clotern "to form clots, to heap on" (c. 1400); related to clot (n.), and perhaps influenced by cluster. Sense of "to litter, to crowd (a place) by a disorderly mass of things" is first recorded 1660s. Related: Cluttered; cluttering.

clutter (n.)

1570s, "things lying in heaps or crowded confusion," from clutter (v.).