Chromatic Adaptation
The visual system's automatic adjustment to the colour of the prevailing light, which keeps familiar objects looking the same colour under different illuminants.
In depth
Adaptation is why photographers consistently underestimate how strong a colour cast is: by the time the shutter is pressed, the eye has already corrected for it. It is also why the correct white balance sometimes looks wrong on screen — the viewer has adapted to the room they are sitting in, not the room in the picture.
Examples in practice
Walking indoors from daylight, the tungsten lamps look strongly orange for a minute and then appear white.