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

The Ultimate Dicitonary Awaits

Expand your vocabulary and dive deeper into language with Merriam-Webster Unabridged.

1. Expanded definitions
2. Detailed etymologies
3. Advanced search tools
4. All ad-free

Discover what makes Merriam-Webster Unabridged the essential choice for true word lovers.

Start Your Free Trial Now