An Etymological Dictionary of Astronomy and Astrophysics

The fraction of the Sun’s area occulted by the Moon. It should not be confused with → eclipse magnitude,
which is the fraction of the Sun’s diameter occulted by the Moon. Eclipse obscuration may be expressed as either a percentage or a decimal fraction (e.g., 50% or 0.50) (F. Espenak, NASA).

See also: → eclipse; obscuration, verbal noun from → obscure.