Wearing good clothes, chosen with care, that suit the person and the occasion. It is not about being rich, and it is not really about being fashionable either, though the dictionary often says 'fashionable' — a well-dressed older man in a plain suit that fits him perfectly is well-dressed, and someone wearing this season's most expensive jacket that hangs badly on them is not. The idea underneath is fit, cleanliness, and good judgement about what goes together. The word feels slightly formal and slightly old-fashioned, and it is more often said about someone than to them; younger people are more likely to say someone 'dresses well' or 'has good style'. It usually describes people, but you will also see it used lightly of a crowd or a place — 'a well-dressed audience'. Compare it with well-groomed, its close neighbour: well-dressed is about the clothes, well-groomed is about the hair, nails and skin. A person can easily be one and not the other.