fog line

/F AA1 G L AY0 N/
noun
  1. 1

    A line painted on a road (usually bright white) that marks the edge of the legally drivable portion.

  2. 2

    The boundary of a body of air, contacting the earth's surface, that has fallen below the dew point and usually contains fog.

  3. 3

    A division in altitude above which fog appears.