1 Physiology. The translucent, yellowish, gelatinous substance of the thyroid follicles. The colloids hold the protein thyreoglobulin, the precursor of the thyroid hormones triiodothyronine and thyroxine.
2. Chemistry. Particles which are extremely fine dispersed in a medium. The particles have a size of 1 to 1000 nm. The particles as well as the medium can be a solid, liquid, or gas. Examples for colloids are paints, milk, and fog.