Rectifier \Rec"ti*fi`er\ (r?k"t?*f?`?r), n.

1. One who, or that which, rectifies.

2. Specifically:
   (a) (Naut.) An instrument used for determining and rectifying the variations of the compass on board ship.
   (b) (Chem.) A rectificator.

Source: Webster's Revised Unabridged Dictionary (1913)