When the boy or grown-up learns learns what one might call special technical languages, e.g., the use of charts and diagrams, descriptive geometry, chemical symbolism, etc., he learns more language-games. (Remark: The picture we have of the language of the grown-up is that of a nebulous mass of language, his mother tongue, surrounded by discreet and more or less clear cut language games, the technical languages.)
6).   Asking for the name: we introduce new forms of building stones. B points to one of them & asks, “What is this?”; A answers, “This is a … ”. Later on A calls out this new word, say “arch”, & B brings the stone. The words, “This is a … ” together with the pointing gesture we shall call ostensive explanation or ostensive definition. In case 6) a generic name was explained, in actual fact, the name of a shape. But we can ask analogously for the proper name of a particular object, for the name of a colour, of a
numeral
number
, of a direction.