Veiling Glare
A diffuse haze of scattered light that lowers contrast across the whole frame without forming distinct shapes.
In depth
Veiling glare is the more damaging half of flare because it is easy to miss on a small screen yet it robs the file of its deepest blacks and desaturates colour. Its usual sources are light striking the front element from outside the frame, a dusty or fingerprinted lens, and internal reflections from the barrel. A hood and a clean front element fix most of it.
Examples in practice
A backlit landscape looks flat and grey until a deep hood is fitted, at which point the shadows regain their density.