Is being a gnostic atheist illogical?

[Angrboda]

I was always under the impression that 'gnostic atheist' was the generally accepted term for someone who was 100% sure there is no God, a 7 on Dawkin's scale. An 'agnostic atheist' would be someone who doesn't believe in God but doesn't feel they can be 100%. I call myself an agnostic atheist and would consider myself a 6.9 on Dawkin's scale.

Is that not how you use those terms?

There's no uniform consensus on what different terms for atheists are, and what those terms specifically mean.

Depending on the atheist, the "definitely know there are no gods" may be termed atheist, strong atheist, gnostic atheist, anti-theist, or even not necessarily atheist at all (it appears from my polling that at least one in ten atheists believes that to be an atheist, you must reject all supernatural claims and beliefs; such an atheist would deny that a person who denies gods yet is open to telepathy is a true[TM] atheist).