1. An action or use for which something is suited or designed.
2. An activity or role assigned to someone or something: "The function of a lawyer is to advise a client of his legal rights."
3. A social gathering or ceremony; especially, a formal or official occasion: "There are many functions that the head of a state must attend."
4. A quality or characteristic that depends upon and varies with another quality.
5. The action or purpose performed by an organ, part, or substance of the body: "It is the function of the heart to pump blood through the body's system."
6. The characteristic action of a compound due to its composition or structure.
7. Etymology: from Middle French fonction, from Old French function, from Latin functio, functionis, "performance, execution"; from functus, past participle of fungi, "perform, execute, discharge".

To operate or to perform properly: "When a fuse breaks down, an electrical circuit stops functioning."

"A clock or watch functions as a means of keeping time."

"An overcoat functions as a way to keep warmer in cold weather."

In mathematics, the Greek letter δ (lowercase) or Δ (uppercase); often used to represent a small distance or a small change in the value of a variable or function.

A standard measure of the responses of the eyes to monochromatic (one color) light at various wavelengths: As part of her research, the ophthalmologist, Dr. Robinson, studied the changes in the luminosity functions of the eyes of her patients.

The human tongue and its functions

About the only interest a person has in the tongue is when something abnormal happens; such as, when there is pain or if some unusual taste factor exists as when there is burning from excessive heat, when accidentally bitten, or when exposed to strong flavors which are spicy, bitter, sweet, sour, etc.

Since the human tongue usually stays out of sight, it is is not considered as valuable as other sensory parts of the body, but if people think they can get along without their tongues, they should re-evaluate this misconception.

For example, when a person extends the tongue out of the mouth and lightly clamps on it between the teeth, then if that person tries to talk, let him/her see if speech under such circumstance can be understood.

A tongue is particularly important with the mastication, or chewing, of food by rolling it around in the mouth so such materials are evenly broken up and made more acceptable to the stomach for digestion. A tongue assists in swallowing when the front part presses against the hard palate in the roof of the mouth. This is followed by having the back part of the tongue hump up, thrusting food into the passage that leads to the esophagus.

Although it may seem to be a simple activity, it is really a necessary function that is conducted by nerves and executed by intricate muscles. A person usually knows how to swallow before being born, which is an indication of how important the swallowing reflex is to one's existence.

Speaking is another consideration because a person must be trained for such extraordinary neuromuscular activities. A baby normally experiments with sounds for two, or more, years before being able to form simple sentences. As people get older, the tongue is able to flex itself into many various shapes for more complex expressions.

Anyone who would like to get a better idea of the tongue's complex activities should concentrate on its various movements while talking.

A slab of mucous membrane enclosing a complex array of muscles and nerves

The upper surface of the tongue has an array of papillae (puh PIL lee), or tiny projections, some of which contain taste buds. Also, arranged among the taste buds are taste cells, which actually receive the sensations of taste.

On the underside of the tongue is a tiny cord, the frenulum, and if it is too short, it holds back normal movements which is known as being "tongue-tied". People with this problem once went through their lives with garbled speech; however, today, this defect can be corrected with surgery.

The tongue is an organ that gives people a great deal of service but too often it is held in low esteem. Normally, people pay less attention to the tongue than they do to their hair or fingernails which are not nearly as important to their well-being.

Despite such neglect, the tongue usually continues to tirelessly function as it tastes and talks throughout our lives.

More facts about the tongue

The tongue has about 10,000 taste receptors.

• They are called taste buds, but "taste hairs" would be a more accurate name in that these receptors project like hairs from the walls of the tiny trenches that run between the bumps on your tongue.
• When you eat, the receptors send signals to the brain, which translates the signals into combinations of sweet, bitter, salty, and sour tastes.

Newborn babies have few taste buds.

• Soon after birth, more buds begin to grow, an by early childhood they cover the top and some of the bottom of the tongue, as well as areas in the cheeks and throat.
• Since young children have many more taste buds blooming in their mouths than adults, they frequently find foods to be too bitter or too spicy.
• Some adults seek out bitter or spicy foods because of a declining number of taste buds.
• In children and adults, each taste bud lives a matter of days before it is replaced.

Different parts of the tongue are sensitive to different tastes.

• The four primary tastes; such as, sweet, bitter, salty, and sour, are each associated with a specific area on the tongue.
• The tip of the tongue is most sensitive to sweet and salty tastes, while sour seems to register more strongly on the sides of the tongue.
• Far to the rear of the tongue, grouped in a V-shape, are most of the receptors for bitter tastes.

The taste buds account for less than twenty percent of the flavors of food.

• The sense of smell, with its own separate receptors, mostly determines what we experience as taste.
• The temperature and texture of food also contribute to its overall flavor.
• Oddly one's sensitivity to saltiness and bitterness seems to increase as food cools, sensitivity to sweetness increases with heat.
• A piece of chocolate may have very little taste when cold, taste fine at room temperature, but seem unpleasantly sweet when hot and half-melted.