To make something new by combining different things together, like ideas or chemicals.
When you synthesize something, it can make people think of science, creativity, and making new things.
Examples:
I will synthesize the red and blue paint to make purple.
She can synthesize different ideas to make a new story.
The scientist will synthesize the chemicals to make medicine.
I will synthesize all the different fruits to make a super fruit!
He can synthesize all the colors in the world to make a rainbow potion.
The wizard will synthesize a new spell to help his friends.