As readers, we recognize prefixes, like dis-, in-, non- and un-, as expressing negation. We immediately know that “unfair” means “not fair.” However, there are some clear exceptions to these rules. Such anomalies can cause confusion for a few reasons. For one, the prefix in- also literally means in, such as inquire, inclose, and insure. The word impromptu for instance comes directly from the Latin phrase in promptu that means “in readiness.”
One particularly tangled example of negative prefixes is the pair ravel and unravel. The word ravel comes from the Dutch word ravelen meaning to tangle or unweave. The word simultaneously means to disentangle and to entangle because in sewing as you unwind a thread, it becomes tangled.
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