Not wearing a coat or lacking a coat; without an outer layer of clothing.
English compound: 'coat' (from Old French 'cote') + '-less' (Old English suffix meaning 'without'). The suffix '-less' has been productive in English since Old English times for negation.
The '-less' suffix is one of English's most powerful word-building tools—you can add it to almost any noun to mean 'without' that thing, which is why we can say 'coatless,' 'homeless,' and even invented words like 'tableless' that people instantly understand!
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