aggro

Short definition from Wiktionary

Noun

1. 1
   Aggravation; bother.
2. 2
   Aggressive behaviour; loud, intimidating behaviour that convincingly threatens violence without necessarily actually becoming violent.
3. 3
   A measure of how belligerent a player is – a high value may inspire either avoidance or preemptive hostile action from enemies.
4. 4
   Hostile attention from an enemy that should target players with better defenses.

Adjective

1. 1
   Angry.
2. 2
   Liable to attack without being attacked first (said of monsters).
3. 3
   Designed for aggressive play that seeks to defeat the opponent in the early stages of the game. (of a player) Favoring such decks.
4. 4
   Hardcore, aggressive.

Verb

1. 1
   To become aggressive towards the player's character.
2. 2
   To cause (a non-player character) to become aggressive towards the player's character.