Photosynthesis is a process in which plants use sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. The plants use glucose as food to grow and release oxygen into the air. For example, a tree uses photosynthesis to make glucose and release oxygen.
Very Simple Definition:
Photosynthesis is how plants make food using sunlight. They take in carbon dioxide from the air and water from the ground, and with the help of sunlight, they turn it into food and release oxygen. For example, a tree uses sunlight to make food and release oxygen.