pi

¹pi

noun \ˈpī\

plural pis \ˈpīz\

Definition of PI

1

: the 16th letter of the Greek alphabet — see alphabet table

2

a : the symbol π denoting the ratio of the circumference of a circle to its diameter

b : the ratio itself : a transcendental number having a value rounded to eight decimal places of 3.14159265

Origin of PI

Middle Greek, from Greek pei, of Semitic origin; akin to Hebrew pē pe

First Known Use: 1638

Other Alphabet Terms

cuneiform, linear, minuscule, pictograph, rune, symbology, wedge

Rhymes with PI

ay, aye, bi, Bligh, buy, by, bye, chai, chi, cry, die, dry, dye, eye, fie, fly, fry, guy, hie, high, Huai, i, I, lie, lye, my, nigh, phi, pie, ply, pry, psi, rye, scythe, shy, sigh, sky, Skye, sly, spry, spy, sty, Tai, Thai, thigh, thy, tie, try, vie, why, wry, wye, xi, Y

²pi

noun \ˈpī\

plural pies

Definition of PI

1

: type that is spilled or mixed

2

: a pi character or matrix

Variants of PI

pi also pie \ˈpī\

Origin of PI

origin unknown

First Known Use: circa 1659

³pi

verb

piedpi·ing or pie·ing

Definition of PI

transitive verb

: to spill or throw (type or type matter) into disorder

intransitive verb

: to become pied

Variants of PI

pi also pie

First Known Use of PI

1889

⁴pi

adjective

Definition of PI

1

: not intended to appear in final printing <pi lines>

2

: capable of being inserted only by hand <pi characters>

Variants of PI

pi also pie

First Known Use of PI

circa 1940

PI

abbreviation

Definition of PI

1

Philippine Islands

2

private investigator

3

programmed instruction

pi

noun    (Concise Encyclopedia)

In mathematics, the ratio of the circumference of a circle to its diameter. An irrational number (see also transcendental number), it has an approximate value of 3.14, but its exact value must be represented by a symbol, the Greek letter . Pi is used in calculations involving lengths, areas, and volumes of circles, spheres, cylinders, and cones. It also arises frequently in problems dealing with certain periodic phenomena (e.g., motion of pendulums, alternating electric currents). By the end of the 20th century, computers had calculated pi to more than 200 billion decimal places.