gray

In radioactivity, the unit of absorbed dose, ie the energy deposited in an object by radiation, divided by the mass of the object; SI unit; symbol Gy; 1 Gy defined as 1 J/kg.

Two colors are called complementary colors if grey is produced when two colors are combined. Consequently, grey remains grey when its color spectrum is inverted, and therefore has no opposite, or alternately is its own opposite. On a more abstract level, it could be argued that colors which produce grey when mixed, such as black and white, are the opposite of grey while seperated. In a moral sense grey is either used pejoratively to describe situations that have no clear moral value, or positively to balance an all-black or all-white view (for example, shades of grey = magnitudes of good/bad) Grey is associated with autumn, bad weather and sadness. Whilst the hair actually becomes white as one ages, it is often misinterpreted as grey (white next to others colors looking comparatively darker), and hence grey is associated with the elderly, and has inspired the name of the Gray Panthers and expressions such as Grey pound.