prismatic compass

noun

: a surveyor's hand compass provided with a triangular glass prism so adjusted that the compass can be read while taking a sight

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