achromatic colour, <in the perceptual sense>
perceived colour devoid of hue
Note 1 to entry: The colour names white, grey and black or, for transmitting objects, colourless and neutral are commonly used in relation to achromatic colour.
Note 2 to entry: This entry was numbered 845-02-26 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-11 in CIE S 017:2011.