orcein
(noun)
noun
1. (chemistry) a dye, related to litmus, that is extracted from the lichen Rocella tinctoria; used as a microscopic stain and as a food colouring
(noun)
1. (chemistry) a dye, related to litmus, that is extracted from the lichen Rocella tinctoria; used as a microscopic stain and as a food colouring