- pi, 3.14159265358979323846... - the ratio of the circumference to the diameter of a circle
--1 is a kind of irrational number
- private detective, PI, private eye, private investigator, operative, shamus, sherlock - someone who can be employed as a detective to collect information
--2 is a kind of detective
--2 has particulars:hotel detective, house detective, house dick; inquiry agent; store detective - principal investigator, PI - the scientist in charge of an experiment or research project
--3 is a kind of scientist, man of science
- pi - the 16th letter of the Greek alphabet
--4 is a kind of letter, letter of the alphabet, alphabetic character
--4 is a member of Greek alphabet- protease inhibitor, PI - an antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs
--5 is a kind of antiviral, antiviral agent, antiviral drug
--5 is a part of drug cocktail, highly active antiretroviral therapy, HAART
--5 has particulars:indinavir, Crixivan; nelfinavir, Viracept; ritonavir, Norvir; saquinavir, Invirase - protease inhibitor, PI - an antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs