The term 'Group of Mah-Jongg Tiles' refers to a set of tiles used in the game of Mah-Jongg, which is a Chinese game of skill, strategy, and luck. The crossword solution for this term is 'MELD, ' which is a term used in Mah-Jongg to describe a set of three or four tiles that match in either suit or rank. A MELD is the basic building block of a Mah-Jongg hand, and it is necessary to form a winning hand.