Phi (disambiguation)

Phi (uppercase Φ, lowercase φ, or maths symbol ϕ) is the 21st letter of the Greek alphabet.

Phi or PHI may also refer to:

Mathematics

 * Golden ratio (φ)
 * Phi coefficient, a measure of association for two binary variables introduced by Karl Pearson
 * Euler's totient function or phi function
 * Integrated information theory (IIT) the symbol of which is φ is a mathematical theory of consciousness developed under the lead of the neuroscientist Giulio Tononi

Physics, chemistry and biology

 * Phi meson, in particle physics
 * Magnetic flux (Φ)
 * Peptide PHI (Peptide histidine isoleucine)
 * 6-phospho-3-hexuloisomerase, an enzyme
 * Phenyl group (Φ), a functional group in organic chemistry
 * Pre-harvest interval
 * pH(i), the isoelectric point

Computing

 * Xeon Phi, an Intel MIC microprocessor
 * Φ (Phi) function, in static single assignment form compiler design

Medicine

 * Permanent health insurance, against becoming disabled
 * Protected health information, in US law

Other science

 * Phi phenomenon, in visual perception
 * Krumbein phi scale, for the size of a particle or sediment

Arts and entertainment

 * Phi (KinKi Kids album) (2007)
 * Phi (Truckfighters album) (2007)
 * Sailor Phi, a villain in the Sailor Moon manga
 * Phi, a character in the visual novels Zero Escape: Virtue's Last Reward and Zero Escape: Zero Time Dilemma.
 * Phi: A Voyage from the Brain to the Soul, a book by Giulio Tononi (2012)
 * Phi, a character from Beyblade Burst Turbo, a TV show written by Hiro Morita

Organizations

 * Packard Humanities Institute
 * Paraprofessional Healthcare Institute, a nonprofit organization based in New York City, US
 * Pepco Holdings Inc.
 * Petroleum Helicopters International, an American commercial helicopter operator
 * Philadelphia’s major professional sports teams
 * Philadelphia Eagles of the National Football League
 * Philadelphia 76ers of the National Basketball Association
 * Philadelphia Phillies of Major League Baseball
 * Philadelphia Flyers of the National Hockey League
 * Post-Polio Health International
 * Phi, a collegiate secret society at Princeton University

Other uses

 * Voiceless bilabial fricative (IPA symbol: )
 * Phi, a village in Sesant, Cambodia
 * Phi, ghosts in Thai culture