Rider-Waite-Smith Tarot Card Definitions & Meaning

Three of Cups

Three of Cups is the third Minor Arcana tarot card on the suit of Cups. In some decks the suit is named Chalices instead. This card is used in game playing as well as in divination.

Divination Usage
This card often carries the meaning of joyful social contact, although it may be considered to be rather superficial, unlike the two of the same suit which is considered more personal. There's agreement, general harmony, frivolity, and sometimes it is associated with birth[1], especially if it comes up with other birth-related cards such as The Empress.

Rider-Waite symbolism
This card is very flat. It is unusual in the fact that it has no depth, not even a minimal background mountain or hill as in similar cards, although it is clearly portrayed in the outdoors. This may be symbolical of superficiality and the skin-deep nature of the card.
There's no getting around the party-feel it exudes. In serious matters this may testify to a lack of seriousness, professionalism or even maturity.

In other decks
In the Thoth Tarot deck this card is labeled Abundance, and is associated with the second decan of Cancer, said to be ruled by Mercury.

References
1. Sharman Burke, "Understanding The Tarot: A Personal Teaching Guide", page 66. St. Martin's Press, 1998. ISBN 0312179138