Constitution

From Unofficial Ansalon Wiki

Constitution is part of your character's Score. it is how healthy your character currently is.

You find it displayed as: CON: 14(22) [18] The first being Permanent or Trained stat, the second is current stat due to equipment or spell effects, the last being how high you can train your maximum.

Constitution affects how many hit points you gain when you level, how fast you heal, how likely you are to fight off poisons, and a few other conditions. High constitution is recommended.