Constitution

In the game: help con

What Constitution does for you.

Constitution is your health and stamina. Among other things, it affects:

your bonus hit points, recalculated from your current Constitution and level (they are not rolled per level)
the hit points you regenerate each tick while resting or sleeping
your bonus movement points
your Fortitude saving throws
how quickly you recover from being stunned
improvement or worsening of your mental state, and so your endurance

The game also finds it under: con, constitution, stamina.