I think an "endo" was originally a deliberate "front-wheelie", usually with the brake on, or against a kerb, but some can do them rolling! (I'm basing this on my
mis-spent BMX childhood).
Hence they could evolve into flashier stuff like:
I can endo turn my Dahon. I am scared to do anything more adventurous in case I snap the handlebarpost.
... so going over the bars is probably considered a Failed Endo
Next week: "Cherrypickers"