The hue of that portion of the visible spectrum lying between blue and violet, evoked in the human observer by radiant energy with wavelengths of approximately420 to450 nanometers; a dark blue to grayish purple blue.

• 靛蓝在可见色谱中位于蓝和紫之间的一种色彩，其放射能量能引起人的注意，波长约在420至450微米之间；一种处于深蓝至灰紫之间的蓝