A wallet requiring signatures from several keys before a transaction executes, expressed as a threshold such as three of five.
Why it matters
A multisig protects against any single key being compromised. It does not protect against every signer being shown the same misrepresentation of a transaction — a failure mode seen in more than one large custody incident.
What you can check
The two numbers that matter are the threshold and the signer count, and both are readable on-chain for most implementations. A three-of-five is only meaningfully three-of-five if the five keys are held by different people, on different devices, in different places — which the chain cannot tell you.
Where it showed up
Records in the Incident Tracker that turn on this: WazirX multisig compromise and Ronin bridge validator key compromise.
Not advice. Definitions are for understanding, not instruction. Nothing here is financial, legal, tax or security advice.