(1):

(n.) A minute groove, or channel; a threadlike line, as of color; a narrow structural band or line; a striation; as, the striae, or groovings, produced on a rock by a glacier passing over it; the striae on the surface of a shell; a stria of nervous matter in the brain.

(2):

(n.) A fillet between the flutes of columns, pilasters, or the like.