Both add a point to the one before, and in most sentences you can swap them. The slight difference: moreover tends to add weight to the same argument, while furthermore tends to add a further, separate point. Both are formal — in ordinary prose, "and" or "also" usually reads better than either.
The core difference
They are near-synonyms, and no rule separates them. The tendency, where writers observe one at all, is this:
- moreover — reinforces what you just said, often with something more telling: The plan is expensive. Moreover, it will not work.
- furthermore — adds the next item in a sequence of points: The costs are high. Furthermore, the timeline is unrealistic.
Swap them in either example and nothing breaks. That is a real measure of how close they are.
Both are formal, and both are overused
These belong to legal, academic and official writing. In most other prose they slow a sentence down for no gain, and the plainer alternative is nearly always better: and, also, on top of that, or simply starting a new sentence. Reaching for furthermore to sound serious is one of the commonest tells of padded writing.
Punctuation
Both take a comma when they open a sentence — Moreover, the deadline has moved. When one joins two independent clauses in a single sentence, it needs a semicolon before it and a comma after: The costs are high; furthermore, the timeline is unrealistic. A comma alone there is a comma splice.
The related connectives
- in addition — the neutral, least formal of the group
- besides — adds a point that also brushes the previous one aside
- what is more — the conversational equivalent of moreover
Frequently asked questions
Is there a real difference between moreover and furthermore?
Very little. Moreover tends to reinforce the same argument, furthermore to add a separate point, but they are interchangeable in most sentences.
Do they need a comma?
Yes when they open a sentence. Joining two clauses in one sentence, use a semicolon before and a comma after.
Should I use them at all?
Sparingly. Both are formal, and in ordinary prose "and", "also" or a new sentence usually reads better.