fast red

noun

often capitalized F&R

: any of several fast red azo dyes: such as

a

: a monoazo acid dye that dyes wool and silk red

called also Fast Red A

b

: a monoazo acid dye that dyes wool and silk claret and is used chiefly as a biological stain

called also Bordeaux B, Bordeaux red, Fast Red B

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