Positive/strong atheism ("I believe there is no God") expresses an unproved and unprovable belief, and therefore is incompatible with the scientific method, and with agnosticism.
The above is true for any definition of God.
'Incompatible' is not an accurate word here. 'Incompatible' implies that Atheism conflicts with the scientific method, which it does not. It would be more accurate to say atheism is orthogonal to the scientific method. But even that isn't true.
Saying that God exists is a claim in the positive and requires proof on your part to prove the claim, not proof on my part to disprove the claim. Anyone can make a claim about anything (pigs can fly) and we're not required to provide proof to the contrary in order to say with certainty that pigs cannot fly. Likewise, I can say, "There is no God" without having to prove that God doesn't exist.
The original definition, and defined by those that coined it, to be positively "there is no god" was
"To deny the Gods/god". Ref Encyclopdia Brittannica which goes in to the history of this issue.
Anything else is just atheists trying to get around the logical fallacy it represents, of an unprovable assertion.
Wikipedia definitions better fit the Huxlien idea of an agnostic. The fact is that there are only three concrete states in terms of belief/certainty:
Belief that there is no god. Lack of belief in a god. Belief in a god.
And there are three words that cover these states (four if you include an impersonal god as a valid god, deist).
Atheist Agnostic Theist
Anything else is just confusing terms and definitions and causes unnecessary argument that is unhelpful to debate.
Wikipedia needs to repent.