A bitcoin transaction that has been relayed to nodes in the Bitcoin network but has not yet been incorporated into a block. Also known as “unconfirmed transactions”. It can also refer to a seller who releases goods before a Bitcoin payment has been confirmed on the network, with the assumption that such confirmation will occur.
It is also a sign of trust that the buyer will not double spend the Bitcoin that has been sent. Typically at least six confirmations from the network are required to be fairly certain that a transaction is verified.