Unspent

Unspent is an adjective describing resources that have not been used or consumed. In budgeting and accounting, an amount that remains unspent at the end of a period is commonly referred to as unspent funds or an unspent budget.

In government finance, unspent appropriations may lapse, be rolled over to the next fiscal period, or be surrendered depending on law, policy, and agency rules. In corporate and organizational budgeting, unspent funds are often reviewed for redeployment, reallocation to other projects, or return to a general reserve, subject to approval processes.

In personal finance, unspent money can become savings, investments, or discretionary funds for future periods. The treatment of unspent funds depends on the context and applicable policies, including whether funds are restricted by grant terms, contract obligations, or internal controls.

In cryptocurrency and blockchain contexts, unspent has a specific technical meaning. Unspent transaction outputs, or UTXOs, are outputs from prior transactions that have not yet been spent. They are the building blocks of a cryptocurrency wallet’s balance and are consumed when new transactions are created. The collection of all unspent outputs constitutes the UTXO set, which is used to validate transactions. If the private keys controlling a set of unspent outputs are lost, those funds become inaccessible.

Overall, unspent denotes resources that remain available but unused, with the exact treatment determined by policy, context, and governance.