octodecimo

noun

oc·​to·​dec·​i·​mo

ˌäktōˈdesəˌmō

plural -s

: eighteenmo

—symbol T

Word History

Etymology

Latin, ablative of octodecimus eighteenth, from octodecim eighteen, from octo eight + -decim (from decem ten)

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