card
Transitive Verb[C/U] Both
pl: cardspast: cardedpp: cardeding: carding
The word carries a strong association with structured information and boundaries. Whether it is a credit card, a business card, or a greeting card, the physical form suggests a portable, standardized piece of data or sentiment that is meant to be exchanged or stored. In a social sense, calling someone a card is a dated, whimsical expression. It suggests the person is a source of entertainment or an oddity, much like a wild card in a game, bringing an element of unpredictability to a conversation.
Countable when referring to individual physical objects like a postcard or a credit card. Uncountable when referring to the activity of card playing as a general hobby.