A dinner table was a type of table on which dinner was eaten.
In 2269, while having a conversation with Spock about how a weapon would release a giant energy beam creating an enormous explosion far away, Hikaru Sulu remarked, "If the Kzinti had that, the whole galaxy would be their dinner table." (i.e. they would be able to conquer and take whatever they wished) (TAS: "The Slaver Weapon")