Unconfirmed Transaction
A transaction accepted into the mempool but not yet included in a block; confirmation count is zero.
Unconfirmed transactions are pending in node mempools waiting to be mined/validated. Their reliability depends on network policy (e.g., RBF on BTC), fee competitiveness, and double-spend risk.
"A merchant accepting 0-conf may see a payment disappear if a higher-fee conflicting transaction is mined instead on networks that allow RBF."
To improve confirmation chances: raise fee (where supported), use CPFP, or rebroadcast. Some wallets show fee/priority estimates and conflict warnings.
"Using CPFP, a user spends the unconfirmed output with a high fee to incentivize miners to include both the parent and child."
Related Terms
Mempool
→A temporary storage space in a node for pending transactions that have not yet been included in a confirmed block.
Replace By Fee (RBF)
→A Bitcoin node policy (BIP125) allowing an unconfirmed transaction to be replaced by a new one that pays a higher fee.
Zero Confirmation
→Transactions that have been broadcast to the network but not yet included in a block.
Confirmations
→The number of blocks added to the blockchain since a transaction was included.
All terms and definitions may update as the Cryptionary improves.
