It's the plural of octopus, or it's the number Pi with eight legs.
Either way, it's a great word.
This octopi tshirt is our artist's interpretation of an octopi, on a funny maths t-shirt.
If you like funny t-shirts like this octopi tee, and want to see other maths tshirts, science t-shirts or other geeky tees, we have a very wide selection that you should check out!