The Committee on Colour Terminology appointed in 1941 by the Colour Group of the Physical Society had originally two objectives : (a) to record definitions of terms current in the various groups of people, concerned with colour ; and (b) to examine the possibility of co-ordinating the terms commonly used. Later, in the light of the Committee‘s discussions, a third objective was added : (c) to recommend a consistent terminology. This was a significant step, as the subject of colour has very wide ramifications and there was every reason to expect very great difficulty in even approaching consistency. The report now published* shows that, provided a few key changes are made, the terms used by different technical groups can be embodied in a single scheme which avoids gross ambiguities while keeping the specialized terms of particular interests substantially intact. The nomenclature of colours themselves, as distinct from the terms used in describing and specifying them, was expressly excluded from the Committee‘s consideration.