(1):

(n.) Thin dry scales or scabs upon the body; especially, thin scales exfoliated from the cuticle, particularly of the scalp; dandruff.

(2):

(n.) Hence, the foul remains of anything adherent.

(3):

(n.) Anything like flakes or scales adhering to a surface.

(4):

(n.) Minute membranous scales on the surface of some leaves, as in the goosefoot.