vervain thoroughwort

noun

: a rough-foliaged perennial herb (Eupatorium pilosum) of the eastern U.S. having opposite mostly oblong leaves and an open cymose cluster of white flower heads

The Ultimate Dictionary 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