accidental, occidental

Accidental or accidental means unintentional; happening by chance or mishap--
The overcharge was accidental; we'll have to apologize and refund the money.
The dog walking by was accidental, but we liked the effect, and used it in the ad.

Occidental or occidental describes something western, capitalized when used to refer to the West as a specific place or region, as in Western Hemisphere, in common use meaning Europe and America--
He is researching different aspects of Occidental and Oriental culture.
Not capitalized, possibly,  when used to describe something as western in a general sense ( western still meaning the Western Hemisphere, or Europe and America )--
He is from China, but he has occidental political ideas.

Now that you know that, you can say--
"His description of Europe as Occidental was not accidental; Europe is considered a part of the West."