Plush means thick, soft and expensive-feeling. A plush carpet, a plush hotel, plush surroundings.
It began as a fabric — a long-piled velvet — and became an adjective for anything luxurious, because only the rich could afford the cloth. A plush toy is one covered in that fabric, and plushie is the collector's word for such a toy.
1adjectiveplushThick, soft and expensive-feeling.
“The hotel lobby had plush velvet sofas and thick carpets.”
plush is a quality.
French peluche means fluff or shag, from a Latin root meaning hair. The adjective grew from the costly fabric.
French
peluche — fluff, plush
English, today
plush
From French peluche (“fluff, plush”). The fact that historically (in past centuries) plush upholstery was so expensive as to be socially exclusive undoubtedly connects the senses of "luxurious" and "soft".
Etymology from Wiktionary, CC BY-SA