black rust

noun

1

: a plant rust producing black discoloration

especially : black stem rust

2

: stem rust sense 2

especially : the uredostage of this fungus

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