pi

¹

[ pahy ]

noun

, plural pis.

1. the 16th letter of the Greek alphabet (Π, π).
2. the consonant sound represented by this letter.
3. Mathematics.
   1. the letter π, used as the symbol for the ratio of the circumference of a circle to its diameter.
   2. the ratio itself: 3.141592+.

pi

²

or pie

[ pahy ]

noun

, plural pies.

1. printing types mixed together indiscriminately.
2. any confused mixture; jumble.

verb (used with object)

, pied, pi·ing.

1. to reduce (printing types) to a state of confusion.
2. to jumble.

PI

³

1. Law. personal injury.
2. principal investigator.
3. Also P.I., p.i. private investigator.

Pi.

⁴

or pi.

abbreviation for

1. piaster.

P.I.

⁵

abbreviation for

1. Philippine Islands.
2. Also PI, p.i. private investigator.

pi

¹

/ paɪ /

noun

1. a jumbled pile of printer's type
2. a jumbled mixture

verb

1. to spill and mix (set type) indiscriminately
2. to mix up

PI

²

abbreviation for

1. Philippine Islands
2. private investigator

pi

³

/ paɪ /

noun

1. the 16th letter in the Greek alphabet (Π, π), a consonant, transliterated as p
2. maths a transcendental number, fundamental to mathematics, that is the ratio of the circumference of a circle to its diameter. Approximate value: 3.141 592…; symbol: π

pi

⁴

/ paɪ /

adjective

1. slang.
   short for pious pious

pi

/ pī /

1. An irrational number that has a numerical value of 3.14159265358979… and is represented by the symbol π. It expresses the ratio of the circumference to the diameter of a circle and appears in many mathematical expressions.

pi

1. The irrational number obtained by dividing the length of the diameter of a circle into its circumference . Pi is approximately 3.1416. The sign for pi is π.

Word History and Origins

Origin of pi¹

First recorded in 1835–45; from Greek pî, peî, used in mathematics to represent Greek periphérion periphery ( def )

Origin of pi²

First recorded in 1650–60; origin uncertain

Word History and Origins

Origin of pi¹

C17: of uncertain origin

Origin of pi²

C18 (mathematical use): representing the first letter of Greek periphereia periphery

Example Sentences

Classical computers have managed the calculation for molecules as large as pentacene, a chain of five hydrocarbon rings with 22 electrons in “pi” covalent bonds, which govern the molecule’s shape and reactivity.

From Science Magazine

Most numbers don’t have names, but pi does.

From NewsForKids.net

Today, using sophisticated computers, researchers have come up with trillions of digits for pi, but there is no end.

From Seattle Times

The nerdy holiday, observed on March 14 because the first three digits of pi are 3, 1 and 4, has been recognized by the U.S.

From New York Times

For example, pi times the radius squared, find the area of a circle to calculate pressures on hydraulic cylinders.

From Salon

Related Words

• inquiry agent
• P.I.
• private detective
• private dick
• private eye
• private investigator
• sleuth