The dot on a domino is called a "pip." The term "pip" refers to the small dots or spots that represent numerical values on the ends of domino tiles. These pips are also found on dice and playing cards, and the word "pip" commonly means a spot or speck. In dominoes, each end of the tile contains a number represented by an arrangement of pips, which serve as counting units for scoring and gameplay. Pips are also sometimes called dots or spots informally. So, the correct and technical term for a dot on a domino is a pip.