What does geode mean?
A geode is a rounded hollow in rock, most often lined with crystals such as quartz, amethyst, or calcite. The word is especially associated with mineral collecting and geology, but it is also familiar from classroom activities in which a dull-looking stone is cracked open to reveal a sparkling interior. Although a geode can refer strictly to a crystal-lined cavity, the term may also designate the complete rounded mass containing it. Its visual appeal gives the word a pleasant, slightly collectible association, while its geological meaning remains precise. In general use, people sometimes apply the word loosely to any attractive stone containing crystals, though this is broader than the technical definition. The word is understood in both British and American English, with pronunciation varying mainly in the treatment of the final syllable.
nounA geode is a small, usually rounded hollow in rock lined with crystals, often including quartz, amethyst, or calcite. The term may also refer to the complete mass of rock containing such a cavity.
- A small, usually rounded cavity in rock lined with mineral crystals.
- The complete rounded rock mass containing a crystal-lined cavity.
"The museum displayed a large geode that glittered with purple crystals when it was cut open."
"She split the geode carefully and found a cluster of clear quartz crystals inside."
"In geology, the teacher explained how a cavity develops into a geode as minerals accumulate along its walls."
The standard plural of a geode.
"Several geodes were displayed in cases along the museum wall."
A geode can look like an ordinary dull stone until it is cracked open, revealing a glittering crystal-lined cavern inside.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does geode come from?
The word entered English in the 17th century from French géode. French borrowed it from Greek geōdēs, meaning “earthy” and derived from gē, “earth.” Many English words concerning Earth and its measurement, including geology, geography, and geodesy, share this Greek root.
Related word forms
How geode is actually used
Usually a countable noun. In formal geological usage, it refers specifically to a hollow rock cavity or its mineral lining; in general use, the word is also applied to the whole stone containing such a cavity.
Easily confused with geode
A geode is a crystal-lined cavity in rock, whereas geodesy is the branch of mathematics concerned with measuring the shape and size of Earth.