What is "pi"?

Mathematician: Pi is the ratio of the circumference of a circle to its diameter.

Engineer: Pi is about 22/7.

Physicist: Pi is 3.14159 plus or minus 0.000005

Computer Programmer: Pi is 3.141592653589 in double precision.

Nutritionist: You one track math-minded fellows, Pie is a healthy and delicious dessert!