• WordNet 3.6
    • n geode (mineralogy) a hollow rock or nodule with the cavity usually lined with crystals
    • ***
Webster's Revised Unabridged Dictionary
    • n Geode jē"ōd (Min) A nodule of stone, containing a cavity, lined with crystals or mineral matter.
    • ***
Century Dictionary and Cyclopedia
    • n geode A concretionary stone or pebble, hollow inside, and often having the walls of the cavity lined with crystals. Geodes of quartz are far more common than any others. Geodes are of frequent occurrence in the limestone rocks of various regions, as in the Niagara limestone in western New York, and in the Mississippi valley, in the Keokuk group, which is of Carboniferous age. In this division of the series there is a so-called geode-bed, in which geodes, ranging from 1 to 20 inches in diameter, are abundant. Many of these are beautiful for their agate structure, or for their lining of drusy quartz; some also contain crystallized calcite, dolomite, blende, or pyrites.
    • ***
Chambers's Twentieth Century Dictionary
    • n Geode jē′ōd (min.) a rounded nodule of stone with a hollow interior
    • ***


Webster's Revised Unabridged Dictionary
F. géode, L. geodes, fr. Gr. earthlike; ge`a gh^, the earth + e'i^dos form
Chambers's Twentieth Century Dictionary
Fr.,—Gr. geōdēs, earth-like, earthen—, earth, eidos, form.


In literature:

Not far off is a place here perfect geodes of chalcedony are found.
"Arizona Sketches" by Joseph A. Munk
The geode has a hollow cell within, lined with beautiful crystals of many colors.
"First Across the Continent" by Noah Brooks
A splendid garnet geode, if you please!
"A Summer in Leslie Goldthwaite's Life." by Mrs. A. D. T. Whitney
Des terrains tres-recens, composes d'argile sablonneuse et ferrugineuse, avec geodes de fer hydrate, et du bois fossile, a differens etats.
"Narrative of a Survey of the Intertropical and Western Coasts of Australia] [Volume 2 of 2]" by Phillip Parker King
I have since learned that such stones are found at many points, and that they are called geodes.
"Death Valley in '49" by William Lewis Manly
And you'll have to spend your time collecting geodes to send back for the miserable trash.
"Lippincott's Magazine. Vol. XII, No. 33. December, 1873." by Various
The entire region is an enormously large, perfectly formed, and undamaged geode.
"Cave Regions of the Ozarks and Black Hills" by Luella Agnes Owen
Its crystalline lining was geode-like.
"The Book of the Damned" by Charles Fort
This was a strange place, and in our search we found geodes, petrified snakes, and short sections of fish.
"The Sheep Eaters" by William Alonzo Allen
Celestine occurs in the Triassic rocks of Britain, especially in veins and geodes in the Keuper marl in the neighbourhood of Bristol.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5" by Various
Geode, an irregular shaped stone, containing a small cavity.
"A Manual of the Antiquity of Man" by J. P. MacLean
While geodes grow from the outside inwards, concretions grow outwards from the center.
"The Elements of Geology" by William Harmon Norton

In news:

Organizers of the Lake Geode Challenge, a USA Triathlon-sanctioned event in Geode State Park, are looking for volunteers from 6 am to noon for the July 14 event.
Using a few ingredients from around the house you can turn an ordinary egg into a geode .
A geode is found in nature when a hollow space inside a rock forms crystals along the inside wall of the space.
We love Alexandra Beth's Agate Geode Necklaces.
A close up of one geode.
A trio of geodes gleams on my desk, white crystals glittering in the light.
Geode — the name comes from the Greek (geoides), meaning earthlike, and is a reference to their rounded shape.
Raw Appeal — Geodes, agate, and rough-cut stones step out of geology class and into fashion .
Geodes, agate, and rough-cut stones step out of geology class and into fashion .
Find an eclectic array of handmade bracelets sculpted in geodes, pearls, carved gemstones and other precious stones.
This 20-inch-tall amethyst geode, aglow with glittering violet, was a gift from Cantor.

In science:

For {y} ∈ ∆0 let ϕx0 ,r ({y}) be the mean over the points of geod(x0 , y ) ∩ S (y , r), and extend by linearity to C(∆0 ).
The Baum-Connes conjecture with coefficients for word-hyperbolic groups (after Vincent Lafforgue)
He enriches the definition of the iterated flowers 5.6 by the introduction of uniformly finite families of “control sets” of uniformly bounded diameter, located uniformly close to geod(x, S0).
The Baum-Connes conjecture with coefficients for word-hyperbolic groups (after Vincent Lafforgue)
Using the relationship (2.7), sometimes one can extend the definition of the vector n inner even to those points of the curve where k geod = 0.
Course of differential geometry
Definition 2.3. A geodesic line on a surface is a curve whose geodesic curvature is identically equal to zero: k geod = 0.
Course of differential geometry
By Theorem 2.1 its curvature is given by hΘE u, ui = A(µ, u) (the first term in the curvature formula disappears for a geod esic).
Positivity of direct image bundles and convexity on the space of Kahler metrics