A thing, a device, a physical item or software used to store attributes and credentials. Sometimes incorrectly used to describe the credential itself. For example; a drivers licence, a birth certificate, a door key, a scratchie, a plastic card, a smart-card, a OTP calculator, a digital certificate, a mobile phone or PDA.

Source: http://identityaccessman.blogspot.com/2006/08/identity-dictionary.html