The term 'Not This or That' can be summarized by two crossword solutions: 'OTHER' (5 letters) and 'NEITHER' (7 letters). Both words are used to express the idea of exclusion, meaning that something is not one thing or the OTHER. 'OTHER' is a pronoun used to refer to a person, thing, or idea that is different from the one already mentioned, while 'NEITHER' is an adverb used to indicate that two or more things are not the case. Together, these two words provide a succinct way to express the idea of not this or that.