Knight of Cups: tarot meaning, upright and reversed

A rider on a walking horse carries a cup toward a stream.
Upright
invitation · idealism
An offer or approach carries feeling, charm, and a wish for connection.
Reversed
unreliable promise · disappointment
An attractive invitation may not be supported by consistent action.
In a reading
The position gives this card a particular task: a description of the situation, a challenge, or guidance. Read its image and meaning alongside the other cards and the question that brought them together.
Golden Dawn correspondence
Knight / Prince (chariot): Air of Water. 20 degrees Libra to 20 degrees Scorpio. Court naming differs between decks; this identifies the Book T rank explicitly. This is the attribution in Book T.
Sources
A. E. Waite, The Pictorial Key to the Tarot. These notes are original interpretations of the Waite–Smith imagery, informed by that text.