Describing furniture that has been covered with padding and fabric or leather — soft to sit on rather than bare wood, metal, or plastic. An upholstered chair, an upholstered headboard, an upholstered bench. This is the form of the word you will meet far more often than the verb itself, because it usually works as a description of what a piece of furniture IS.

Two patterns to notice. Alone before a noun it simply means padded and fabric-covered: "a small upholstered stool". With 'in' it tells you the material: "upholstered in grey wool", "upholstered in leather". You will see both all over furniture shops, hotel descriptions, and interior-design writing, where the word does real work — it tells a buyer immediately that a seat is soft and cloth-covered.

Because it can be either an adjective ("the upholstered chairs are more expensive") or the past form of the verb ("they upholstered it last year"), the same word does two jobs. Both are correct; the meaning is the same picture.

There is also that gently humorous use for people — "well-upholstered" meaning comfortably plump. It is old-fashioned and kind rather than rude, but do not use it about someone in front of them.