To mix up in idea, erroneously regard or treat as identical, fail to distinguish; = confuse, v. 5.

transitive. To confuse or muddle (a person, the mind); to render (a thing) more complex, to make obscure; to sully or tarnish (a person, reputation…

To confound (in one's mind) stupidly.

To mix up in the mind, regard as the same, confound with. Obsolete. rare.

transitive. To combine or associate (qualities, ideas, memories, etc.), now esp. inappropriately or confusedly; to confuse with something else.

transitive. To confuse (two things); to confuse (one thing) with another; to mix together mentally.

To mix up in the mind, to fail to distinguish, erroneously regard as identical, mistake one for another; = confound, v. 7.