mix-up

(noun) a mistake that results from taking one thing to be another. Synonyms: confusion. Example: "He changed his name in order to avoid confusion with the notorious outlaw."

(verb) assemble without order or sense. Synonyms: jumble, confuse, mix up. Example: "She jumbles the words when she is supposed to write a sentence."

(verb) cause to be perplexed or confounded. Synonyms: stump, mix up. Example: "This problem stumped her."