reckoner

noun

reck·​on·​er

-k(ə)nə(r)

plural -s

1

: one that reckons

2

: an aid to reckoning

especially : a book of tables

called also ready reckoner

Word History

Etymology

Middle English rikenere, from rikenen to reckon + -ere -er

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