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PI

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

P.I.

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

private investigator

noun
1.
private detective.
Abbreviation: PI, p.i., P.I.
Origin
1935-1940
1935-40
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for p.i

pi1

/paɪ/
noun (pl) pis
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
Word Origin
C18 (mathematical use): representing the first letter of Greek periphereiaperiphery

pi2

/paɪ/
noun (pl) pies
1.
a jumbled pile of printer's type
2.
a jumbled mixture
verb (transitive) pies, piing, pied, pies, pieing, pied
3.
to spill and mix (set type) indiscriminately
4.
to mix up
Word Origin
C17: of uncertain origin

pi3

/paɪ/
adjective
1.
(Brit, slang) short for pious (sense 2), pious (sense 3)

PI

abbreviation
1.
Philippine Islands
2.
private investigator
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for p.i

pi

n.

Greek letter, from Hebrew, literally "little mouth." As the name of the mathematical constant, from 1841 in English, used in Latin 1748 by Swiss mathematician Leonhart Euler (1707-1783), as an abbreviation of Greek periphereia "periphery." For the meaning "printer's term for mixed type," see pie (3).

Online Etymology Dictionary, © 2010 Douglas Harper
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p.i in Medicine

pi (pī)
n. pl. pis

Symbol π The 16th letter of the Greek alphabet.

pI (pē'ī')
n.
The pH value for the isoelectric point of a given substance in solution.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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p.i in Science
pi
  (pī)   
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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p.i in Culture
pi [(peye)]

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.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for p.i

PI

noun
  1. A pimp (1931+)
  2. A private detective; op (1960+)

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Related Abbreviations for p.i

pi

Pali

Pi

inorganic phosphate

PI

  1. performance indicator
  2. politically incorrect
  3. present illness
  4. primary infertility
  5. principal investigator
  6. private investigator
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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