from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Of, relating to, or being a surface characterized by smooth, shell-like convexities and concavities, as on fractured obsidian.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of a type of irregular fracture having planar, concentric curves, like those on a mussel shell. Of a mineral having such a fracture, such as flint.
from the GNU version of the Collaborative International Dictionary of English
- adj. Having elevations or depressions in form like one half of a bivalve shell; -- applied principally to a surface produced by fracture.
from The Century Dictionary and Cyclopedia
- In mineralogy, having convex elevations and concave depressions like shells: applied principally to such a surface produced by fracture, as exemplified in obsidian.
- In mathematics, pertaining or relating to the conchoid: as, Holm's conchoidal screw.
From Greek konkhoeidēs, mussellike : konkho-, concho- + -oeidēs, -oid.(American Heritage® Dictionary of the English Language, Fourth Edition)
From conchoid (Wiktionary)