definition of
[PI]

[1] #1 PI n. [pi] the ratio of the circumference to the diameter of a circle; approximately equal to 3.14159265358979323846.... wn

[2] #2 PI n. [private detective, private eye, private investigator, operative, shamus, sherlock] someone who can be employed as a detective to collect information. wn

[3] #3 PI n. [principal investigator] the scientist in charge of an experiment or research project. wn

[4] #4 PI n. [pi] the 16th letter of the Greek alphabet. wn

[5] #5 PI n. [protease inhibitor] an antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs. wn