From a formal semantic viewpoint: juice is the superclass of grapefruit juice (''grapefruit juice'' ''is-a-kind-of'' ''juice''). In an "is-a"kind-of"-relation one could replace the specific formulation ''grapefruit juice'' with the generic formulation ''juice'', and still have a valid sentence. | From a formal semantic viewpoint: juice is the superclass of grapefruit juice (''grapefruit juice'' ''is-a-kind-of'' ''juice''). In an "is-a"kind-of"-relation one could replace the specific formulation ''grapefruit juice'' with the generic formulation ''juice'', and still have a valid sentence. |