compass card: Meaning and Definition of

com'pass card"

Pronunciation: [key]
— Navig. Navig.
  1. a circular card with magnets attached to its underside, the face divided on its rim into points of the compass, degrees clockwise from north, or both, and floating or suspended from a pivot so as to rotate freely.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.