There are a few monster prefixes found in the game. All monsters have one of these right in front of their names, with different colors.
|Weakest||Pink||~80% or less of yours|
|Weak||Purple||Slightly below or equal to yours|
|Normal||Brown||Slightly above yours|
|Strong||Green||Up to twice yours|
|Awful||Yellow||Up to ~3 times yours|
|Boss||Red||Over 3 times yours|
The prefix of a monster is affected by your cp and the monster's cp. As you grow stronger, monsters' prefixes will become weaker, unless you move to a stronger area. Killing 100 monsters with the BOSS prefix will earn the Boss Slayer achievment. Be aware that there are monsters with the title Region Boss, which are different from monsters with the boss prefix.