Extremely unpleasant, cruel, or brutal in behavior or quality.
From 'beast' (Old French 'beste') plus the suffix '-ly'. The word evolved from describing animal-like behavior to describing anything crude, violent, or disagreeable.
Victorian Londoners used 'beastly' constantly to complain about weather, food, or bad luck—it's a wonderfully dramatic word that tells you exactly how people 150 years ago felt about their problems without swearing.
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