1. Angle between the major axis of polarization and the horizontal. Also called dip or tilt. See polarization ellipse. 2. Rotational motion of a ship or aircraft about a horizontal axis perpendicular to the ship’s course. Compare roll, yaw, and trim. 3. The frequency of sound that is used in conjunction with other senses in virtual reality studies. In addition to frequency, information may be conveyed by volume, duration of a signal, stereo effects, etc.