DEF-Down

DEF-Down is a status ailment that has appeared in several Mario RPGs. It stands for "Defense-Down".

Mario & Luigi: Superstar Saga
Some enemies have the ability to change the Mario Bros. stats. If their defense power goes down, enemy attacks will do more damage. The ailment is indicated by a gray block with an arrow pointing down.

Paper Mario: The Thousand-Year Door
The status ailment returns in this game and serves much the same purpose. It is indicated by a gray diamond with an arrow pointing down. Using a Mr. Softener can give this status effect to enemies, however, the enemies can also do the same to Mario.

Mario & Luigi: Partners in Time
DEF-Down is the same status ailment in this game. Its indicator is a shrinking green circle around the afflicted. Ice Flowers can randomly inflict this status ailment on enemies.