Size-wise what is considered a 'card'?

[steve B]

To me it's something that fits a few criteria.

Was it sold or issued in a series
Is it obviously something else- A coin, a figurine, a plate etc.
Is it medium size or less- narrower than shoulder width, and not overly tall. I'm thinking 11x14 is about the biggest Id think of as a card. So posters are out but the roughly 5x7 cards made from the same art in the 80's are in.
It can't be simply cut down from packaging- The wiffleball boxes with Munson or Scott while collectible aren't cards even if the flap is cut off. But the cards printed 5 to a box are cards.
Other packaging items aren't cards - The Yaz Kielbasa label is cool, but it's not a card.

And there's a bunch of stuff that isn't readily categorized. B18s, silks, Bf2s that sort of stuff.

Steve B