In yesterday's colloquium regarding Vanessa Williamson's Read My Lips: Why Americans Are Proud to Pay Taxes, the word "loophole" came up a lot, because it is important to people's perceptions regarding the supposed regressivity of income taxes in practice.
I've always been bemused by this term, in part because I thought it derived linguistically from knotholes in wood. But apparently it derives instead from narrow vertical holes in walls from which inside defenders could shoot arrows.
Tax experts generally don't use the term "loophole" among themselves, because we consider it too imprecise. We'd be more inclined to discuss tax benefits that might be "unintended," or else intended by someone but poorly rationalized, or else the product of unforeseen interactions between separate provisions or of linguistic ambiguity or formalism in the tax law, etc.
I'm fairly sure I had never once used it in an article, unless perhaps with reference to public opinion, until we used it in Tax Games 1 and Tax Games 2 given the broad readership that we were seeking (as it happened, far more successfully than we had ever imagined was possible).
But one fun thing at yesterday's colloquium was hearing from attendees about parallel terms in other languages. Apparently the German term is "schlupfloch," which (per Wikipedia plus the vagaries of Google Translate) is derived from the term for a small opening from which one can escape from a passage or location.
And the French term is "niche fiscale." We of course have long since borrowed the term "niche" into English, with some broadening of its most literal sense as a shallow recess or nook (more comparable, perhaps, to "schlupfloch" than "loophole"). But in English it would now have a wholly distinct valence.
What do we learn from this? Nothing, I suppose, beyond what we literally learn from this (i.e., what the words are), but that's enough for me.