heat definition In physics, a form of energy associated with the movement of atoms and molecules in any material. The higher the temperature of a material, the faster the atoms are moving, and hence the greater the amount of energy present as heat.
Cilia (singular: cilium) are microscopic, hair-like structures that extend outwardfrom the surface of manyanimal cells. These structures are important in the cell cycle and replication, and cilia play a vital part in human and animal development and in everyday life. A typical cilium is between one and ten micrometers long, and usually less than one micrometer wide.
cilium (pl. cilia) a fine cytoplasmic structure in the form of a thread which projects from the surface of cells. Each cell may bear numerous cilia which beat constantly in one direction, either moving liquid over the surface of the cells concerned or moving the cell(s) in relation to the liquid, for example, locomotion in PROTOZOANS.