A form of colour-blindness in which the proportions of three primary colours (1) that are mixed to match a comparison colour deviate from the normal. Also called anomalous trichromasy, anomalous trichromatism, anomalous trichromatopsia, anomalous trichromopsia. See also Rayleigh equation. Compare anomalous dichromacy. anomalous trichromat n. A person with anomalous trichromacy.