To mix up in a confused or untidy way; to move or act in a confused manner.
Possibly imitative, first appearing in the 16th century. May relate to the sound of things being mixed or shaken together. The noun sense of a confused mixture followed shortly after.
A 'jumble sale' (British) or 'rummage sale' (American) gets its name from the way donated items are literally jumbled together - the chaos is part of the treasure hunt appeal. The word perfectly captures both the physical act of mixing and the mental state of confusion.
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