retroactivity

noun

ret·​ro·​activity "+ 

1

: the quality or state of being retroactive

2

: the capacity of a bacterial agent in biological warfare to react upon the user

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