An avoidable series of events that have a 100% chance of death but do not specifically warn the player of the impending non-obvious trap.
The first video game about Death traps was released in 1984.
This is not merely putting the character in jeopardy or some situation to which there is a solution fight out of the situation, or otherwise weasel ones way out of the trap. Deathtraps are instantly sprung and hopeless. This for things along the lines of running through a normal looking door and falling to ones death due to a missing balcony. The player only knows to avoid this from having fallen victim to it previously. They were not forced to hear "avoid such and such door" and they were encouraged or even required by circumstance to run. This is most common in adventure games (no risk, no adventure, éh?).