A term used in several different senses. Generally speaking, it is applied to anything which agrees with the regular and established type. In chemistry, the term is applied to solutions of acids or bases of such strength that each litre contains the number of grams corresponding to the molecular weight of the substance in question. In physiology the term ‘normal’ is applied to solutions of such strength that, when mixed with a body fluid, they are ISOTONIC and cause no disturbance: for example, normal saline solution.