The mesocarp is the middle layer of a fruit, lying between the outer skin (exocarp) and the innermost core (endocarp). There are several synonyms for the word mesocarp that you can use depending on your context. One common alternative is "pulp," which is often used to describe the fleshy tissue inside fruits like oranges and grapefruits. Another synonym is "pericarp," which refers to the entire fruit wall, including the mesocarp, exocarp, and endocarp. In certain fruits like peaches and plums, the mesocarp is called the "flesh." In still other fruits, such as apples, the mesocarp is called the "hypodermis," which refers specifically to the layer just underneath the outer skin.