Definition from Wiktionary, the free dictionary
layer (plural layers)
- A single thickness of some material covering a surface.
- Wrap the loaf in two layers of aluminum foil before putting it in the oven.
- After the first coat of paint dried, he applied another layer.
- A (usually) horizontal deposit; a stratum.
- I find seven-layer cake a bit too rich.
- A person who lays things, such as tiles.
- A mature female bird, insect, etc. that is able to lay eggs.
- When dealing with an infestation of headlice, the first step is to eliminate the layers.
- A hen kept to lay eggs.
- A shoot of a plant, laid underground for growth.
- (stratum): stratum
Derived terms 
single thickness of some material covering a surface
item of clothing worn under or over another
person who lays things, such as tiles
hen kept to lay eggs
shoot of a plant
- (transitive, intransitive) to cut or divide (something) into layers
- (transitive, intransitive) to arrange (something) in layers.
- Layer the ribbons on top of one another to make an attractive pattern.
to cut or divide into layers
to arrange in layers
- layer in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
- layer in The Century Dictionary, The Century Co., New York, 1911