leuco bases

Colourless compounds formed by reduction of triphenylmethane dyes. Generally, they are amino or hydroxy derivatives of triphenylmethane. Use of this class name, which is more or less parochial to the technology of dyes, is not endorsed. E.g. (p-Me2NC6H4)2CHPh, the leuco base of Malachite Green.
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1347 (https://doi.org/10.1351/pac199567081307)