pi meaning and definition

PI noun

Definition of pi (noun)

1. the ratio of the circumference to the diameter of a circle; approximately equal to 3.14159265358979323846...
2. someone who can be employed as a detective to collect information
   • synonyms: operative, private detective, private eye, private investigator, shamus, sherlock
3. the scientist in charge of an experiment or research project
   • synonyms: principal investigator
4. the 16th letter of the Greek alphabet
5. an antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs
   • synonyms: protease inhibitor