[col.loid] n [ISV coll- + -oid] (ca. 1852) 1: a gelatinous or mucinous substance found in tissues in disease (as in the thyroid) or normally
2. a: a substance that consists of particles dispersed throughout another substance which are too small for resolution with an ordinary light microscope but are incapable of passing through a semipermeable membrane b: a mixture consisting of a colloid together with the medium in which it is dispersed "smoke is a ~" -- col.loi.dal adj -- col.loi.dal.ly adv