from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. flat; even; applied to surfaces and spaces in which the definitions, axioms, and postulates of Euclid respecting parallel straight lines are assumed to hold true.
from The Century Dictionary and Cyclopedia
- In geometry, similar to a plane; flat; having real points at all real distances, but none at imaginary distances.
Ancient Greek ὁμαλός (homalos, "even, level") + + -oid. (Wiktionary)