Biochemistry

• PP_i, the anion P₂O₇⁴⁻, a Pyrophosphate
  Pyrophosphate
  In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Any salt or ester containing two phosphate groups is called a diphosphate. As a food additive, diphosphates are known as E450.- Chemistry :...
  
  
• PPI, Peptidyl prolyl cis-trans-isomerase, a human chaperone (protein)
• PPI, a right-handed form of polyproline helix, a secondary structure in proteins

Indicators and indexes

• Pareto priority index
  Pareto Priority Index
  The Pareto priority index , so named because of its connection with the Pareto principle, which is in turn named after the economist Vilfredo Pareto, can be used to prioritize several projects. It is especially used in the surroundings of six sigma projects...
  
  , an index to prioritize projects
• Plan Position Indicator
  Plan position indicator
  The plan position indicator , is the most common type of radar display. The radar antenna is usually represented in the center of the display, so the distance from it and height above ground can be drawn as concentric circles...
  
  , a display of tactical information from RADAR or other sources.
• Producer Price Index
  Producer price index
  A Producer Price Index measures average changes in prices received by domestic producers for their output. It is one of several price indices.Its importance is being undermined by the steady decline in manufactured goods as a share of spending....
  
  , a metric used in economics, related to inflation

Medicine

• Patient package insert
  Package insert
  A package insert or prescribing information is a document provided along with a prescription medication to provide additional information about that drug.-Responsible agencies:In the United States, the Food and Drug Administration determines the requirements...
  
  , a document included with certain prescription medications
• Prepulse inhibition
  Prepulse inhibition
  Prepulse Inhibition is a neurological phenomenon in which a weaker prestimulus inhibits the reaction of an organism to a subsequent strong startling stimulus . The stimuli are usually acoustic, but tactile stimuli Prepulse Inhibition (PPI) is a neurological phenomenon in which a weaker...
  
  , the ability of the nervous system to attenuate the startle response when a warning stimulus is given
• Proton-pump inhibitor, a drug that reduces gastric acid secretion in the stomach
• Psychophysiological Interaction
  Psychophysiological Interaction
  Psycho-Physiological Interactions or PPI is a brain imaging method of estimating the effective connectivity, or functional coupling, between a brain region and the rest of the brain with relation to the performance of a particular psychological task....
  
  , an analysis technique for identifying task-related functional connectivity between brain regions

Organizations

• Italian People's Party (1919–1926)
  Italian People's Party (1919–1926)
  The Italian People's Party was a Christian-democratic political party in Italy.It was founded in 1919 by Luigi Sturzo, a Catholic priest. The PPI was backed by Pope Benedict XV to oppose the Italian Socialist Party...
  
   (Partito Popolare Italiano), precursor of the Christian Democracy party
• Italian People's Party (1994–2002) (Partito Popolare Italiano), one of the successor parties of Christian Democracy
• Peace Party of India
  Peace Party of India
  The Peace Party is an Indian political party in the state of Uttar Pradesh. It represents people who are striving for betterment of downtrodden people of India through political awareness and participation in governance...
  
  , Indian political party in the state of Uttar Pradesh
• Philips Phonographische Industries, the original name for Philips Records
  Philips Records
  Philips Records is a record label that was founded by Dutch electronics company Philips. It was started by "Philips Phonographische Industrie" in 1950. Recordings were made with popular artists of various nationalities and also with classical artists from Germany, France and Holland. Philips also...
  
  
• Phonographic Performance (Ireland) Limited
  Phonographic Performance (Ireland) Limited
  Phonographic Performance Limited controls the public performance, broadcasting, and other rights in hundreds of thousands of different recordings on thousands of different labels in the Republic of Ireland....
  
  
• Pirate Parties International
  Pirate Parties International
  Pirate Parties International is the political international of the Pirate Party movement. It was formally founded in 2010 at the PPI conference in Brussels, Belgium.-Aims:The PPI statutes give its purposes as:...
  
  , umbrella organization of the international Pirate Party movement
• Primarily Primates
  Primarily Primates
  Primarily Primates is a non-profit organization in Bexar County, Texas, that operates an animal sanctuary, housing 600 non-human primates and a variety of other animals retired from use in Entertainment, Research or as rescues from the Exotic Pet Trade...
  
  , an animal sanctuary for non-human primates in Texas, United States.
• Professionals Party of India
  Professionals Party of India
  The Professionals Party of India is a small political party set up in India in 2007. It was registered with the Election Commission of India in 2008 and starting receiving international attention in the aftermath of the 2008 Mumbai attacks. Its main support is from India's middle class and its...
  
  , an Indian political party registered with the Election Commission of India
• Progressive Policy Institute
  Progressive Policy Institute
  The Progressive Policy Institute is a think tank in the United States, founded in 1989 which styles itself as promoting the ideas of "New Democrats." It covers a very wide range of issues and describes itself as centrist, although progressive critics frequently describe it as conservative,...
  
  

Science and technology

• Parallel Peripheral Interface
  Parallel Peripheral Interface
  The Parallel Peripheral Interface is a peripheral found on the Blackfin embedded processor.The PPI is a half-duplex, bi-directional port that is designed to connect directly to LCDs, CMOS sensors, CCDs, video encoders , video decoders or any generic high speed, parallel device.The width of the...
  
  , a connection for driving LCD displays on processors such as the Blackfin
• Picks per inch, a unit of textile measurement
• Pixels per inch, the pixel density of devices such as computer displays, image scanners, and digital cameras
• Plan Position Indicator
  Plan position indicator
  The plan position indicator , is the most common type of radar display. The radar antenna is usually represented in the center of the display, so the distance from it and height above ground can be drawn as concentric circles...
  
  , a map-like display on a cathode ray tube device for radar applications
• pp I, a branch of the Proton–proton chain reaction