n The 16th letter of the Classical and Modern Greek alphabets and the seventeenth in Old Greek.
n (mathematics) An irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its diameter; approximately 3.14159265358979323846264338327950; usually written π.
n (letterpress typography) Metal type that has been spilled, mixed together, or disordered.
n (typography) pica (conventionally, 12 points = 1 pica, 6 picas ≈ 1 inch).
n Piaster.
n (historical) A county of Chengdu, Sichuan, China.
n Abbreviation of Piauí., a state of Brazil. [A state of the Northeast Region, Brazil. Capital: Teresina]
n Initialism of Prison Industries (the prison-run work program for inmates)
n (US, Philippines, historical, dated) Initialism of The Philippine Islands.
n (informatics, SGML, XML) Initialism of processing instruction.
n Initialism of partial induction (see AI)
n Initialism of personal injury. [(law) An injury to the body, mind or emotions, as opposed to an injury to property.]
n Initialism of politically incorrect (see PC)
n Initialism of principal investigator (lead researcher on a grant-funded project) [(sciences) lead researcher on a grant-funded project]
n Initialism of private investigator. [An agent hired by a private party for the purpose of investigation or evidence gathering.]
n (biochemistry) Abbreviation of phosphatidylinositol (a phospholipid component of eukaryotic cell membranes, also abbreviated in PtdIns) [(chemistry) a phospholipid containing inositol]
n (pharmacology) Initialism of protease inhibitor. [(pharmacology, virology) A class of drugs used to treat or prevent infection by viruses such as HIV and hepatitis C.]
n (organic chemistry) Initialism of polyimide. [(chemistry) Any polymer whose monomers are imides; used to make high-temperature resins]
n (medicine) Initialism of ponderal index. [An anthropometric statistic that combines the height and weight of an individual, similar to the body mass index.]
n (electronics) Initialism of power integrity.
n Abbreviation of prohibited immigrant.
n (fan fiction category) Initialism of pseudoincest. [(erotica) Erotica or other fiction focused on sexual situations between family members who are not blood relations, (e.g., siblings by adoption, stepparents and stepchildren, in-laws).]
n (automotive) Initialism of port injection. (fuel injection)
n (psychology) Initialism of paradoxical intention. [(psychotherapy) A psychotherapeutic technique used to treat anxiety by repeatedly rehearsing the anxiety-inducing pattern of thought or behaviour, often with exaggeration and humor.]