A polo neck (UK) or turtle neck (US) or skivvy (Australia) is a garment—usually a sweater—with a close-fitting, round, and high collar that folds over and covers the neck. It can also refer to type of neckline, the style of collar itself, or be used as an adjective ("polo necked").

A simpler variant of the standard polo neck is the mock polo neck (or mock turtle neck), that resembles the polo neck with the soft fold at its top and the way it stands up around the neck, but both ends of the tube forming the collar are sewn to the neckline. This is mainly used to achieve the appearance of a polo neck where the fabric would fray, roll, or otherwise behave badly unless sewn. The mock polo neck clings to the neck smoothly, is easy to manufacture, and works well with a zip closure.

Turtleneck-like garments have been worn for hundreds of years, dating to the 15th century at least.

From the late 19th century on, turtlenecks were commonly worn by menial workers, athletes, sailors and naval officers. Since the middle of the 20th century black polo necks have been closely associated with radical academics, philosophers, artists and intellectuals. Polo necks also became a big fashion for young wealthy men after they were worn by European film stars Marcello Mastroianni and Yves Montand.

Polo (Persian: چوگان‎, chowgan) is a team sport played on horseback in which the objective is to score goals against an opposing team. Sometimes called, "The Sport of Kings", it was started by Persians and was popular till 1979 which declined sharply due to invasion of Arabic Muslims in Iran. Players score by driving a small white plastic or wooden ball into the opposing team's goal using a long-handled mallet. The traditional sport of polo is played at speed on a large grass field up to 300 yards long by 160 yards wide, and each polo team consists of four riders and their mounts. Field polo is played with a solid plastic ball, which has replaced the wooden ball in much of the sport. In arena polo, only three players are required per team and the game usually involves more maneuvering and shorter plays at lower speeds due to space limitations of the arena. Arena polo is played with a small air-filled ball, similar to a small soccer ball. The modern game lasts roughly two hours and is divided into periods called chukkers. Polo is played professionally in 16 countries. It was formerly, but is not currently, an Olympic sport.

The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective (from Latin) signifying "of the neck" is cervical (though this more frequently used to describe the cervix).

The cervical portion of the human spine comprises seven boney segments, typically referred to as C-1 to C-7, with cartilaginous discs between each vertebral body. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In addition, the neck is highly flexible and allows the head to turn and flex in all directions. From top to bottom the cervical spine is gently curved in convex-forward fashion. It is the least marked of all the curves of the column.

In the middle line below the chin can be felt the body of the hyoid bone, just below which is the prominence of the thyroid cartilage called "Adam's apple", better marked in men than in women. Still lower the cricoid cartilage is easily felt, while between this and the suprasternal notch the trachea and isthmus of the thyroid gland may be made out. At the side the outline of the sternomastoid muscle is the most striking mark; it divides the anterior triangle of the neck from the posterior. The upper part of the former contains the submaxillary gland also known as the submandibular glands, which lies just below the posterior half of the body of the jaw. The line of the common and the external carotid arteries may be marked by joining the sterno-clavicular articulation to the angle of the jaw.