An electronic payment instrument is the means through which a customer submits an electronic payment instruction to a payment service provider. It may consist of hardware, digital software or a specified method of interaction established by agreement between the customer and the provider. The instrument is used to initiate the movement of monetary value, but is distinct from both the payment account used in the transaction and the transfer carried out by the provider.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.