How do you spell Drier

Available Definitions:
1)  n. - One who, or that which, dries; that which may expel or absorb moisture; a desiccative; as, the sun and a northwesterly wind are great driers of the earth.
2)  n. - Drying oil; a substance mingled with the oil used in oil painting to make it dry quickly.
3)  superl. - Alt. of Driest