Small openings in laws, rules, or agreements that allow people to escape requirements or obligations; also, narrow windows in castle walls.
From 'loop' (possibly from Middle English 'loup' meaning to leap, or an old Germanic source) and 'hole.' Originally referred to narrow defensive slits in castle walls; the metaphorical meaning developed as people found ways to 'slip through' laws.
Loopholes are kind of the immune system's vulnerability—they exist because rules are written in human language, which is gloriously ambiguous! Lawyers and accountants literally make six figures just by reading rules really carefully and finding the wiggle room!
Complete word intelligence in one call. Free tier — 50 lookups/day.