What does crystal mean?
A crystal is a solid material—such as quartz, salt, sugar, or diamond—whose atoms are arranged in a highly ordered, repeating pattern that extends in all directions, giving crystals their distinctive flat faces and geometric shapes. This precise structural sense dominates scientific writing in chemistry, physics, and geology. Beyond science, the word has two familiar everyday senses: a piece of naturally occurring transparent mineral, especially rock crystal used in jewelry, and fine, clear colorless glass prized for tableware, decanters, and chandeliers. The word also appears in the fixed expressions 'crystal clear,' meaning perfectly transparent or easy to understand, and 'crystal ball,' the sphere traditionally associated with fortune-telling. Derived forms include 'crystalline' and 'crystallize.' With roots in the ancient Greek word for ice, 'crystal' bridges the natural world of minerals and the refined world of craftsmanship, making it equally at home in a laboratory report and an elegant dining room.
A solid substance with atoms arranged in a highly ordered, repeating lattice structure, giving it a characteristic geometric form.
"Quartz is one of the most common minerals on Earth and forms beautiful six-sided crystals."
This is the primary scientific sense, dominant in chemistry, physics, and geology.
Clear, colorless glass of high quality, used for fine tableware, ornaments, and decorative objects.
"They toasted the newlyweds with flutes of sparkling crystal."
Often implies lead crystal, though modern 'lead-free' varieties are widely sold.
The transparent cover over the face of a watch or clock.
"He replaced the scratched crystal on his vintage wristwatch."
Standard plural applies across senses: mineral specimens, pieces of glassware, and watch covers all take 'crystals.' When referring to glassware collectively, 'crystal' can function as an uncountable mass noun ('a set of crystal').
"The cave walls were studded with glittering crystals of calcite."
The word 'crystal' comes from the Greek 'krystallos,' meaning 'ice' — ancient Greeks believed rock crystal was ice frozen so deeply it could never melt again.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of crystal
Crystal derives from the ancient Greek 'krystallos,' meaning 'ice' or 'clear ice,' which itself likely relates to 'kryos,' meaning frost or icy cold. The Greeks applied the term to rock crystal (clear quartz) because they believed it was ice frozen so permanently that it could never thaw. Latin adopted the word as 'crystallum,' from which Old French 'cristal' developed before entering Middle English around the medieval period. Cognates and derivatives include 'crystalline,' 'crystallize,' and 'crystallography,' all tracing back to the same Greek root.
Related word forms
How crystal is actually used
In everyday speech, 'crystal' most often refers to either the mineral sense or high-quality glassware. In scientific contexts (chemistry, physics, geology), it carries the precise meaning of a solid with an ordered internal lattice structure. The adjective phrase 'crystal clear' is extremely common idiomatically, meaning perfectly transparent or easy to understand. In British English, 'crystal' as glassware often implies lead crystal, while US usage extends more broadly to any fine glass.
Easily confused with crystal
Chrystal is an obsolete or erroneous spelling of crystal, which is the correct modern spelling for both the mineral and the glassware.