Other forms: crystals
A crystal is a solid whose atoms line up in a regular repeating pattern, which is why crystals grow with flat faces and sharp angles. Salt, sugar, quartz and snowflakes are all crystals.
The word also means very clear glass of high quality — crystal glasses, lead crystal — and by extension anything perfectly transparent, which is where crystal clear comes from. In some traditions crystals are used for healing or divination, and crystal ball is the fixed phrase for fortune telling. Note that crystallise means both to form crystals and, figuratively, to become suddenly clear: the idea crystallised on the way home.
1nouncrystalA solid whose atoms are arranged in a regular repeating pattern.
“Salt forms cubic crystals.”
2nounhighVery clear high-quality glass.
“The crystal glasses only come out at Christmas.”
3adjectiveperfectlyPerfectly clear.
“The water was crystal clear right to the bottom.”
Too few real examples of this word to estimate which sense is commonest.
crystal is a solid with a regular structure.
Greek krystallos meant clear ice, from a root meaning frost. The Greeks believed quartz was water frozen so hard it would never melt, and the word for ice became the word for the stone and then for anything with the same clarity.
Proto-Indo-European
*krews- — hard, hard outer surface, crust
Ancient Greek
κρύσταλλος — clear ice
Old French
cristal
Anglo-Norman
cristall
Old English
cristalla
Middle English
crystal
English, today
crystal
Built from
From Middle English crystal, cristal, criȝstall, representing a merger of Old English cristalla (from Latin crystallus) and Anglo-Norman cristall, Old French cristal (from Latin crystallum). The Latin is derived from Ancient Greek κρύσταλλος (“clear ice”), from κρύος (“frost”), from Proto-Indo-European krews- (“hard, hard outer surface, crust”).
Etymology from Wiktionary, CC BY-SA