A bright red dye. A source was the tree found in Ceylon and India (*Caesalpinia braziliensis); it was used in the English wool industry until the 15c. A later source was the Caesalpinia tree (Caesalpinia echinata) of South America. In later times, the dye gave its name to the country of Brazil.
Cf. Scarlet
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.