Other forms: confused, confusing, confuses
To confuse somebody is to mix their thoughts up so they no longer understand. Confuse the issue, I was confused, that confused everybody.
It also means to mistake one thing for another: confuse the two, do not confuse cause with effect. Confuse with is the construction for that sense. Note confused, describing the person; confusing, describing the cause; and confusion, the state. The pair confused and confusing is the same -ed and -ing distinction as bored and boring, and is one of the commonest learner errors.
1verbconfuseTo mix somebody's thoughts up so they do not understand.
“The new signage confused about half the visitors.”
2verbmistakeTo mistake one thing for another.
“People confuse the two constantly and the names do not help.”
confuse is a mixing up.
Latin confundere means to pour together — con-, together, plus fundere, to pour. Confuse and fuse are the same verb, and confusion began as a physical mixing before it became a mental one.
Proto-Indo-European
*ǵʰewd-
Latin
cōnfūsus
Anglo-Norman
confus
Middle English
confused — frustrated, ruined
English, today
confuse
a back-formation from confused, from Middle English confused (“frustrated, ruined”), from Anglo-Norman confus, from Latin cōnfūsus, past participle of cōnfundō.
Etymology from Wiktionary, CC BY-SA