Meltdown vs. Melt Down
The closed form is a noun, including literal nuclear and figurative failure/upset senses. The open form is verbal, including literal melting and figurative loss of function.
Use “meltdown” as a noun naming an event or state. Use “melt down” as a verb phrase describing the action or process.
Key details
Choose the right form
| Meaning / context | Use | Decision |
|---|---|---|
| noun naming an event, failure, or extreme upset | meltdown | Use the closed noun. |
| verb meaning to melt material or lose function | melt down | Keep the verb and particle separate. |
| before a noun | meltdown | Use the noun form when the grammar requires a noun. |
Quick tests
Decision test
Does the expression name an event or state rather than describe what something does?
If yes: Use the noun “meltdown.”
If no: If it describes an action/process, use “melt down.”
Caveat: Word class is the safest test. Keep nuclear, emotional, system-failure, and literal-material senses distinct in context.
Examples
The server outage caused a scheduling meltdown.
“Meltdown” is a noun naming a breakdown.
The old metal can be melted down for reuse.
“Melt down” functions as a verb phrase.
The system began to melt down under the load.
The open form describes an action or process.
Further guidance
Core difference
Use the closed noun.
Fast Test
Use the noun “meltdown.” If it describes an action/process, use “melt down.”
Usage Boundary
Word class is the safest test. Keep nuclear, emotional, system-failure, and literal-material senses distinct in context.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- meltdown (opens in a new tab)Cambridge University Press · Meltdown is a noun for a nuclear core accident, a complete system/financial failure, or informally an episode of extreme upset.
- melt something down (opens in a new tab)Cambridge University Press · Melt down is a phrasal-verb construction for heating something until it becomes liquid, and can also describe a system losing its ability to operate.