the elevation above which snow remains on the ground year-round, ie the lower boundary of a permanent snowcap. Sometimes also used to designate the lower elevation boundary of merely seasonal snowfields.
The general altitude to which the continuous snow cover of high mountains retreats in summer, chiefly controlled by the depth of the winter snowfall and by the temperature of the summer.
In astronomy, a snowline is a theoretical distance from a star that, during the system's formation, material must orbit outside of in order for a planet core to form.