(Greek: around, enclosing, surrounding, about, near, close; often used as a prefix)

Surrounding the kidney in whole or part.
Inflammation of the cellular tissue around the kidney.
perinephrium (s), perinephiria (pl)
The connective and fatty tissue that envelops or surrounds a kidney.
perineum (s), perinea (pl)
1. The area between the thighs extending from the coccyx to the pubis and lying below the pelvic diaphragm.
2. The external surface of the central tendon of the perineum, lying between the vulva and the anus in the female and the scrotum and the anus in the male.
Pertaining to or suffering from perineuritis.
Inflammation of the perineurium.
perineurium (s), perineuria (pl)
1. The sheath of connective tissue enclosing a bundle of nerve fibers.
2. An intermediate layer of connective tissue in a peripheral nerve, surrounding each bundle (fasciculus) of nerve fibers.
Near or around a node.
Near or around a nucleus.
Near or around the eye.
period (s) (noun), periods (pl)
1. A rather large interval of time that is meaningful in the life of a person, in history, etc., because of its particular characteristics.
2. Any specified division or portion of time: poetry of the period from 1603 to 1660.
3. A round of time or series of years by which time is measured.
4. A round of time marked by the recurrence of some phenomenon or occupied by some recurring process or action.
5. The point of completion of a round of time or of the time during which something lasts or happens.
6. A specific length of time during school hours that a student spends in a classroom, laboratory, etc., or has free.
7. Any of the parts of equal length into which a game is divided.
8. The time during which something runs its course.
9. The present time.
10. The point or character (.) used to mark the end of a declarative sentence, indicate an abbreviation, etc.; a full stop.
11. A full pause, as is made at the end of a complete sentence; a full stop.
12. A sentence; especially, a well-balanced, impressive sentence.
13. A term used to indicate an occurrence of menstruation.
14. A time of the month during which menstruation occurs.
15. The basic unit of geologic time, during which a standard rock system is formed.
16. The duration of one complete cycle of a wave or oscillation; the reciprocal of the frequency.
17. A musical division of a composition, usually a passage of eight or sixteen measures, complete or satisfactory in itself, commonly consisting of two or more contrasted or complementary phrases ending with a conclusive cadence.
18. In astronomy, "a period of rotation"; the time in which a body rotates once on its axis or "a period of revolution"; the time in which a planet or satellite revolves once about its primary.
19. Noting, pertaining to, evocative of, imitating, or representing a historical period or the styles which are current during a specific period of history; such as, period costumes; a period play.
20. Used by a speaker or writer to indicate that a decision is irrevocable or that a point is no longer discussable: "I forbid you to leave, period."
21. Etymology: A "course or extent of time", from Modern Latin periodus, "recurring portion, cycle", from Latin periodus, "a complete sentence"; also "cycle of the Greek games" from Greek periodos, "rounded sentence, cycle, circuit, period of time"; literally, "going around", from peri-, "around" plus hodos, "a going, a way, a journey".

Sense of "repeated cycle of events" led to that of "interval of time". Meaning "dot marking end of a sentence" first recorded in 1609, from a similar use in Modern Latin. Sense of "menstruation" dates from 1822. Educational sense of "portion of time set apart for a lesson" is from 1876. Used in the sporting sense is attested from 1898.

periodic (adjective) (not comparable)
1. Recurring at intervals of time; such as, periodic revivals of an interest in etymology.
2. Occurring or appearing at regular intervals.
3. Repeated at irregular intervals; intermittent.
4. In physics: Recurring at equal intervals of time.
5. With reference to a mathematical function, having a graph that repeats after a fixed interval (period) of the independent variable.
6. In astronomy, characterized by a series of successive circuits or revolutions, as the motion of a planet or satellite and pertaining to a period, as of the revolution of a heavenly body.
7. A reference to or characterized by rhetorical periods, or periodic sentences.
periodical (s) (noun), periodicals (pl)
A publication that appears at fixed intervals (daily, weekly, monthly, or yearly).
periodically (adverb), more periodically, most periodically
1. Repeatedly at regular times: "The equipment should be periodically tested each week."
2. At stated times: "The festival is periodically celebrated in the community."
periodicity (s) (noun), periodicities (pl)
1. The recurrence of something at regular intervals.
2. Similarity between the properties of chemical elements that are close to each other in the periodic table.

Related "around, round, surrounding" units: ambi-; ampho-; circ-; circum-; cyclo-, -cycle; gyro-.