Multisignature Wallet
A wallet that requires several separate keys to approve a transaction, such as two of three or three of five.
The requirement is enforced by the blockchain itself, through a script or a smart contract, so the rule cannot be bypassed by the software that displays the wallet. Multisignature setups are standard for project treasuries, decentralized organizations, and funds, because they remove any single person or device as a point of failure. Good practice separates signers across people, locations, and device types, and defines in advance how a lost key is replaced. Because the arrangement is visible on chain, outside observers can verify how many approvals a given treasury requires.
In practice
A treasury configured as three of five requires any three of its five designated signers to approve before a transfer is broadcast.
The common misunderstanding
Multisig distributes control rather than eliminating it; if enough signers collude or are compromised at once, the funds move normally.