King of Cups
Upright
Fair man, man of business, law, or divinity; responsible, disposed to oblige the Querent; also equity, art and science, including those who profess science, law and art; creative intelligence.
Reversed
Dishonest, double-dealing man; roguery, exaction, injustice, vice, scandal, pillage, considerable loss.
A. E. Waite, The Pictorial Key to the Tarot (1911), Part III §2The picture
He holds a short sceptre in his left hand and a great cup in his right; his throne is set upon the sea; on one side a ship is riding and on the other a dolphin is leaping. The implicit is that the Sign of the Cup naturally refers to water, which appears in all the court cards.
Older readings
Beware of ill-will on the part of a man of position, and of hypocrisy pretending to help. Reversed: Loss.
A. E. Waite, The Pictorial Key to the Tarot (1911), Part III §4. Waite collected these and says they often disagree with the main meanings.Waite wrote in 1911 and some of his meanings show it. Tarot is a tradition of reflection, not a prediction, and no card decides anything for you.