1. Tendency or progress southward; as, the southing of the sun.
2. The time at which the moon, or other heavenly body, passes the meridian of a place.
3. (Science: astronomy) distance of any heavenly body south of the equator; south declination; south latitude.
4. (Science: astronomy) distance southward from any point departure or of reckoning, measured on a meridian; opposed to northing.