1. forms into crystals or takes on a crystalline structure
Usage: British spelling
2. becomes clear and definite in form or expression
Usage: British spelling; figurative

Examples

• The salt crystallises as the water evaporates.
• Sugar crystallises when the syrup cools down.
• Her ideas began to crystallise after the meeting.
• The plan crystallises into a concrete proposal.
• Opposition to the policy crystallises among voters.
• The solution crystallises overnight in the laboratory.