1. The ratio of the circumference to the diameter of a circle; approximately equal to 3.14159265358979323846... Noun
2. Someone who can be employed as a detective to collect information Noun
3. The scientist in charge of an experiment or research project Noun
4. The 16th letter of the Greek alphabet Noun
5. An antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs Noun