(Greek: around, enclosing, surrounding, about, near, close; often used as a prefix)
It should be noticed that this peri- prefix is not related to the Greek peri- elements listed in this section. It is discussed here in order to clarify its origin and to clear up any confusion that may exist about its connection to the Greek prefix form.
For more than a century (from about 1660 to 1780) decorative heads of false hair were almost universally worn by fashionable men and women in Europe. In English, such headdresses were called perukes or periwigs. Both words are derived from Italian perruca, which originally meant "bushy head of hair" and later "wig".
Perruca was borrowed into French as perruque, which developed into two forms in English, peruke and periwig, which are synonymous. Periwig was shortened to wig, which is the form now in common use. The meaning of false hair, wig is first recorded in 1606, from the original use of false perruke (1565-1573).
2. Any of various behavioral and physiological changes in an organism in response to the amount of daylight to which the organism is exposed; for example, the relative length of day and night on a seasonal or daily basis.
2. Injection of a gas into the peritoneal cavity as a diagnostic or therapeutic measure.