(1):

(n.) A substance (as albumin, gum, gelatin, etc.) which is of a gelatinous rather than a crystalline nature, and which diffuses itself through animal membranes or vegetable parchment more slowly than crystalloids do; - opposed to crystalloid.

(2):

(a.) Resembling glue or jelly; characterized by a jellylike appearance; gelatinous; as, colloid tumors.

(3):

(n.) A gelatinous substance found in colloid degeneration and colloid cancer.