Question: what are jumbo index playing cards?
Answer: 'Jumbo' naturally means large, and 'Index' means the way the ranks (A,K,Q,J,10,9, 8, etc.) and suits (Spades, Hearts, Diamonds, and Clubs) are printed on the cards. So, 'Jumbo Index' means the ranks, and suit symbols are printed larger on the cards than the more traditional 'Standard Index'.