Warm and stuffy in an unpleasant or musty way; characterized by a close, warm atmosphere often with stale air (British).
Derived from 'frowst' (verb meaning to lounge in a stuffy room), itself possibly from Romance language roots or folk etymology, mainly used in British English.
This is one of those brilliantly specific British words that non-British speakers often don't have a direct equivalent for—it's not quite 'stuffy,' not quite 'musty,' but exactly that particular British interior atmosphere of warmth and staleness.
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