Meaning of “plaster” - Learner’s Dictionary

plaster

noun uk us /ˈplɑːstər/
WALLS [ U ]

a substance that is spread on walls in order to make them smooth

FOR CUTS [ C ] UK (US trademark Band-Aid)

a small piece of sticky material that you put on cuts on your body

be in plaster

UK (US be in a cast) If your arm or leg is in plaster, it is covered in a hard, white substance to protect a broken bone:

She had her leg in plaster for three months after the accident.

(Definition of “plaster noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)