1. Immersion of the body or any of its parts in water or any other yielding or fluid medium, or application of such medium in any form to the body or any of its parts. 2. Apparatus used in giving a bath of any form, qualified according to the medium used, the temperature of the medium, the form in which the medium is applied, the medicament added to the medium, or according to the part bathed. 3. Fluid used for maintenance of metabolic activities or growth of living organisms, cells derived from body tissue.