Endo- is a prefix referring to something internal in the body, e.g. endokrinology (secretion inside the body). Endo is the opposite of ecto.

In cycling, an endo is a trick that involves the rider lifting the rear wheel into the air while the front wheel stays grounded. It is similar to another trick called the stoppie, and is sometimes called a front wheelie. One is performed by locking the front brake and leaning forward. The rider then tries to balance by shifting his weight and keeping the rear wheel as high as possible. If the rider does not have a front brake, he then just jams his foot in between the tire and front fork while pushing forward.

"Endo" can also refer to a violent wipeout caused by improperly landing with the front wheel first after a jump. With the rear wheel in the air, a moving bike has the tendency to throw the rider over the handlebars while flipping end over end (hence the name).

"Endō" (遠藤) is the family name of Shusaku Endo, a twentieth century Japanese author of several critically acclaimed novels.