Without color; transparent or clear, or used figuratively to mean dull and uninteresting.
From 'colour' (noun) + '-less' (suffix meaning 'without'). The '-less' suffix comes from Old English and is one of the oldest word-building tools in the language, used to create opposites.
Water is technically 'colorless' in small amounts but appears blue in large quantities because water molecules absorb red wavelengths—a property that explains why deep oceans and lakes are blue even though the H2O itself has no color!
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