A person or thing that confuses someone; something that causes confusion or makes understanding difficult.
From confuse + -er (agent noun, one who does the action). The -er suffix, from Old English, attaches to verbs to name the person or thing performing the action.
A great confuser in language is the English apostrophe—it creates confusion because the same punctuation mark means two completely different things: 'its' (possessive) has no apostrophe, but 'it's' (it is) must have one, yet people constantly flip them.
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