to misunderstand the meaning, intention, or significance of (something or somebody)
to estimate (something) wrongly
to identify (somebody or something) wrongly
I mistook him for his brother
to confuse (somebody or something) with another
to choose (something) wrongly
She mistook her way in the dark
mistakable adj
[Middle English mistaken from Old Norse mistaka to take by mistake, from mis-1 + taka to take]