The word rarely turns up outside that context.
and
The word rarely turns up outside of that context.
Which one is correct and why?
The word rarely turns up outside that context.
and
The word rarely turns up outside of that context.
Which one is correct and why?
The preposition/adverb, outside, and the compound preposition, outside of, both have the same meaning: beyond the boundaries/limits of _
The New Oxford American Dictionary provides an excellent exposition on the usage of these two:
Outside of tends to be more commonly used in the US than in Britain, where outside usually suffices, but, like its cousin off of, it is colloquial and not recommended for formal writing. … The adverb outside is not problematic when referring to physical space, position , etc. (I‘m going outside), but the compound preposition outside of is often used as a colloquial (and often inferior) way of saying except for, other than, apart from (outside of what I just mentioned, I can’t think of any reason not to). Besides possibly sounding more informal than desired, outside of may cause misunderstanding by suggesting physical space or location when that is not the point to be emphasized, or when no such sense is intended — consider the ambiguity in this sentence: outside of China, he has few interests. Does this mean that his primary interest is China? Or does it mean that whenever he is not in China, he has few interests?
'Outside of' grates on my ear too! The 'of' is superfluous - and I was brought up to believe that brevity is the key to good writing: so unnecessary words should be omitted.
Let's consider two sentences: 1. Outside/Outside of Norway, the world's largest Norse community is in Minnesota. 2. The cemetery is located outside/outside of the town. In these two sentences, the term outside/outside of is used in two different ways. In the first sentence it means "apart from" or "anywhere other than in." Because the synonymous phrase ends with a preposition, the best term here is "outside of." In the second sentence it means "beside" or "alongside." The best term here, I think, is "outside." To summarize, if you could substitute the words "apart from" or other than in," use "outside of." If you could substitute the word "beside" or "alongside," use "outside." I hope this is helpful.