What is crystallise?

Some articles on crystallise, crystallises:

Floating Charge - Remedies - Crystallisation
... a floating charge at all - the charge must first crystallise into a fixed charge ... in the relevant document, a floating charge crystallises either upon the appointment of a receiver or upon the commencement of liquidation ... Stocks and Securities Investments Co Ltd v Manila Rly Co that a charge should also crystallise upon the company ceasing to trade as a going concern ...

More definitions of "crystallise":