Synergism is when two or more things work together to make a bigger effect than they would alone.
Synergism is usually a very good thing. It means things are working together to make something better.
Examples:
The team showed great synergism in their game.
The music and the dancing had a lot of synergism.
The two friends had great synergism when they worked together.
The cake and the ice cream had a lot of synergism at the party.
The superhero team had amazing synergism when they fought the bad guys.
The two machines had great synergism and made a lot of things very fast.