tongue, muscular organ occupying the floor of the mouth in vertebrates. In some animals, such as lizards, anteaters, and frogs, it serves a food-gathering function. In humans, the tongue functions principally in chewing, swallowing, and speaking. The human tongue is covered by a mucous membrane containing small projections called papillae, which give it a rough surface. Tiny taste organs, or buds, are scattered over the surface of three of the four types of papillae, with large numbers concentrated on papillae found on the back and sides of the tongue. The appearance of the tongue is often an indication of body health; a pinkish-red color is normal. In impairment of the digestion and in certain feverish diseases, a yellowish coating forms. Local infection of the tongue is called thrush.

painted tongue: see salpiglossis.

adder's-tongue, name for a fern genus (Ophioglossum). Adder's-tongues are classified in the division Pteridophyta.

Muscular organ on the floor of the mouth. It is important in motions of eating, drinking, and swallowing, and its complex movements shape the sounds of speech. Its top surface consists of thousands of raised projections (papillae). The receptors of taste (taste buds) are embedded in the papillae and are sensitive to four basic flavours: sweet, salty, sour, and bitter. More specific flavours are influenced by the sense of smell. The tongue's appearance (e.g., coated or red) can give clues to disease elsewhere. Disorders of the tongue include cancer (often caused by smokeless tobacco), leukoplakia (white patches), fungal infection, and congenital disorders. Different animals use the tongue to serve varied functions; for example, frogs have an elongated tongue adapted to capturing prey, the snake's tongue collects and transfers odours to a specialized sensory structure to help locate prey, and cats use their tongues for grooming and cleaning.

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