“Not logical”, which by definition does not apply to math.
“Not a ratio”, e.g., a number that cannot be written as the division (ratio) of two whole numbers.
It should be no surprise to anyone, that calculus deals with the latter, but the title would allude to the article dealing with the former.
It was "alogos" (later "arritos"), with the meaning "inexpressible", "which cannot be spelt out" - in the sense that you can never fully write out e.g. the square root of two the way you can a natural or a rational number like 2/3 or 1/4.
Unfortunately "alogos" also meant "illogical", so that's where the confusion stems...
> Greek mathematicians termed this ratio of incommensurable magnitudes alogos, or inexpressible.