Power-emoting or god-emoting (also called "god moding") is an act of forcing the result of one's actions on another character, typically without the other player's consent and not giving the other character a chance to do anything about the emote. For instance, "Player1 kills Player2", "Player1 hits Player2" and "Player1 steals X gold from Player2" are all power-emotes.
Power-emoting is heavily frowned upon in most roleplaying communities, since it takes the freedom of action away from the player being emoted on. The typical solution for this issue is to emote attempts instead of finished actions. For example, typing "Player1 tries to stab Player2 in the chest with his sword" will give Player2 a chance to dodge or parry the blow.
Some standard in-game emotes, such as /spit or /slap, can be considered power-emotes.