Meaning of “layer” - Learner’s Dictionary

layer

noun [ C ] us uk /leɪər/

B2 an amount of a substance covering a surface, or one of several amounts of substance, each on top of the other:

the outer/top layer
Place alternate layers of pasta and meat sauce in a shallow dish.
The shelf was covered in a thick layer of dust.

More examples

layer verb [ T ]

[ often passive ] The potatoes are layered with onion.

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