mix up

Verb

WordNet 3.0

Verb (2)

assemble without order or sense“She jumbles the words when she is supposed to write a sentence”Synonyms: jumble confuse mix up
cause to be perplexed or confounded“This problem stumped her”Synonyms: stump mix up

Webster's Dictionary (GCIDE)

mix up \mix up\ n.

1.To confuse the identities of (two or more objects); to mistake (one object for another); as, at the family gathering he mixed up his two nieces, to their great amusement. [PJC]

2.To mix together; -- usually implying a mistake, whether done intentionally or unintentionally; as, the mixed up this year's receipts with last year's, and it took hours to find the right ones. [PJC]