pie

UK: /ˈpaɪ/ US: /paɪ/ ,(pī)

WordReference Random House Learner's Dictionary of American English © 2026

pie¹ /paɪ/   n. 

1. Food a crust of baked dough, filled with fruit, pudding, etc.:
   [countable] an apple pie.
   [uncountable] had apple pie for dessert.
2. Food a layer cake with a cream or custard filling:
   [countable] a Boston cream pie.
   [uncountable] Our desserts include lemon meringue pie and Boston cream pie.
3. a total or whole that can be divided:
   [countable] They want a bigger piece of the pie.
4. an activity or affair:
   [countable] I'm sure he had a finger in the pie.

Idioms

5. Idioms easy as pie, extremely easy or simple:
   Stealing the money was easy as pie.
6. Idioms pie in the sky, [uncountable] a plan, suggestion, idea, or belief about something not likely to come true:
   His new tax plan is just pie in the sky.

WordReference Random House Unabridged Dictionary of American English © 2026

pie¹  (pī), n. 

1. Food a baked food having a filling of fruit, meat, pudding, etc., prepared in a pastry-lined pan or dish and often topped with a pastry crust:
   apple pie; meat pie.
2. Food a layer cake with a filling of custard, cream jelly, or the like:
   chocolate cream pie.
3. a total or whole that can be divided:
   They want a bigger part of the profit pie.
4. an activity or affair:
   He has his finger in the political pie too.
5. Food pizza.
6. Idioms easy as pie, extremely easy or simple.
7. Idioms nice as pie, extremely well-behaved, agreeable, or the like:
   The children were nice as pie.
8. pie in the sky:
   • Idioms the illusory prospect of future benefits:
     Political promises are often pie in the sky.
   • Idioms a state of perfect happiness;
     utopia:
     to promise pie in the sky.

• Middle English, of obscure origin, originally 1275–1325

pie′like′, adj. 

pie²  (pī), n. 

1. Birds magpie.

• Latin pīca, akin to pīcus woodpecker
• Old French
• Middle English 1200–50

pie³  (pī), n., v.t., pied, pie•ing. 

1. Printing pi².

pie⁴  (pī), n. 

1. Religion (in England before the Reformation) a book of ecclesiastical rules for finding the particulars of the service for the day.

Also, pye. 

• 1470–80; translation of Latin pīca pie²; the allusion is obscure; compare pica¹

pie⁵  (pī), n. 

1. Currency a former bronze coin of India, the 12th part of an anna. Cf. naya paisa, paisa, pice. 

• Marathi pā'ī literally, a fourth
• 1855–60

PIE, 

1. Language Varieties Proto-Indo-European.

Collins Concise English Dictionary © HarperCollins Publishers::

pie / paɪ/ noun

1. a baked food consisting of a sweet or savoury filling in a pastry-lined dish, often covered with a pastry crust
2. pie in the sky ⇒ illusory hope or promise of some future good; false optimism

Etymology: 14th Century: of obscure origin

pie / paɪ/ noun

1. an archaic or dialect name for magpie

Etymology: 13th Century: via Old French from Latin pīca magpie; related to Latin pīcus woodpecker

pie / paɪ/ noun , verb

1. a variant spelling of pi2

WordReference Random House Learner's Dictionary of American English © 2026

pi¹ /paɪ/   n. [countable] , pl. pis. 

1. Linguistics the 16th letter of the Greek alphabet (&Pgr;, π).
2. Mathematics
   • the letter π, used as the symbol for the ratio of the circumference of a circle to its diameter.
   • the ratio itself, a number usually given as 3.141592+.

WordReference Random House Unabridged Dictionary of American English © 2026

pi¹  (pī), n., pl. pis. 

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

• Greek pî, peî; used in mathematics to represent Greek periphérion periphery
• 1835–45

pi²  (pī), n., pl. pies, v., pied, pi•ing. 
n. 

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

v.t. 

3. Printing to reduce (printing types) to a state of confusion.
4. to jumble.

Also, pie. 

• origin, originally uncertain 1650–60

PI, 

1. Law personal injury.
2. principal investigator.
3. private investigator.

Pi., 

1. piaster.

Also, pi. 
P.I., 

1. Place Names Philippine Islands.
2. Also, p.i. private investigator.

Collins Concise English Dictionary © HarperCollins Publishers::

pi / paɪ/ noun (pis)

1. the 16th letter in the Greek alphabet (Π, π), a consonant, transliterated as p
2. 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

Etymology: 18th Century (mathematical use): representing the first letter of Greek periphereia periphery

pi, pie / paɪ/ noun (pies)

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

verb (pies, piing, pied, pies, pieing, pied)(transitive)

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

Etymology: 17th Century: of uncertain origin

pi / paɪ/ adjective

1. 
   short for pious2,