1. relating to or denoting a line on the Earth's surface where the magnetic needle has no inclination and points horizontally
Usage: technical; geography/geophysics

Examples

• The aclinic line runs roughly along the geographic equator.
• Navigators must account for magnetic variation when crossing the aclinic line.
• At the aclinic line, a compass needle remains horizontal rather than dipping.
• The position of the aclinic line shifts slowly over geological time.
• Ships traveling along the aclinic line experience minimal magnetic inclination.