Resembling a cobweb.
In biological terms it refers to a “a cobwebby remnant of the partial veil which in some mature mushrooms hang from the edges of the cap.”
Probably from the Latin cortina (also the noun form) meaning curtain.
"Each dress in the Gothic Lolita shop was adorned with cortinate lace.”
Love Tahlia, who wishes there really were such a shop in her vicinity.