Synergize is a powerful word that expresses the idea of achieving more by working together. However, if you're looking for synonyms to vary your language, there are several options to choose from. Collaborate is one possibility, suggesting that two or more people are working together towards a common goal. Another synonym could be cooperate, which similarly implies a spirit of collaboration and teamwork. Harmonize is another option, which suggests that different elements are working together in balance and unity. Finally, the word integrate could be used to convey the idea of combining different parts into a cohesive whole. All these words can be used interchangeably with synergize, depending on the context and tone of your message.