What is another way of saying furthermore?

Here are some alternatives to "furthermore," depending on the context and desired tone:

Formal:

* Moreover

* In addition

* Additionally

* Besides

* What's more

* Also

* As well

* On top of that

* To add to that

Informal:

* And

* Plus

* Also

* Too

* On top of it

* Not only that, but

* What's more

More specific:

* Specifically

* In particular

* For instance

* To illustrate

The best choice depends on the specific sentence and the overall tone of your writing.