In the business world, Synergy is used most often referring to people or projects: two (or more) people working together or two (or more) projects whose joint efforts are related. It refers to an interaction whose efforts will result in a mutual benefit.
This is one of the most strongly disliked buzzwords, and yet one of the few which is being used as its original meaning. The etymology of the word is quite literally “work with”, and is applied in corporate as well as scientific contexts.
Its main problem – as far as I can see – is its tremendous over-use. People are sick of it.
So if you do want to use the word Synergy, I say go ahead. However, if you are worried about your the occasional eye-rolling or cringe-inducement, then you have a couple of options.
You can simply say “collaboration”, “alliance” or any other such word.
Even better: work out in your mind what the mutual benefit of collaboration may be, and express a specific action or outcome.