UPD

Unplanned Dismount. A low-speed, unexpected step-off: failed mount, awkward turn, loss of balance while maneuvering, or a small stumble where you leave the wheel and walk it off.

The term comes from traditional unicycling, where speeds are low and stepping off is normal. On EUC, use it carefully. At 5 km/h (3 mph), UPD makes sense. At 40 km/h (25 mph), you crashed.

Why EUC riders use different words

At low speed, a UPD is exactly what the name says - you step off, maybe stumble, and recover. At speed, the useful words are crash, faceplant, slide, or bail. The traditional unicycle vocabulary does not scale cleanly to EUC velocities.

555 take

Use UPD for small, low-speed exits. Do not use it to soften a serious incident. At walking speed, sure - you had an unplanned dismount. At 50 km/h (31 mph), you had a crash. Call it what it is.