What is "pi"?

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!