"Reversed" is a term used when reading the tarot cards, or any other card oracle, such as angel cards, etc. A card is said to be reversed when the images on the card appear upside down.
When reading playing cards, or even some of the older style tarot cards, sometimes it is hard to tell from just the pips on the card whether it is reversed or upright. The reversed meaning of a tarot card doesn't always mean "opposite" of the upright meaning, but it can. Some readers feel that a reversed card is the same meaning, but that the outcome is likely to be delayed or challenged in some way. Other readers don’t use reversed meanings at all. It’s a matter of preference — but including reversed meanings in your readings gives you a whole new set of definitions with which to work, and that can greatly enhance the message from the cards. A card that is reversed is also said to be contrary, challenged, inverted or ill-dignified.