A type of structural protein found within the cytoplasm of eukaryotic cells which forms one type of cell cytoskeleton. In mammalian cells, the intermediate filaments are intermediate in width between actin (a muscle protein) and microtubules. There are six types of intermediate filaments: keratins, desmins, vimentins, glial filaments, neurofilaments, and nuclear lamins.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.