Relating to or characteristic of a conspiracy or plot; of the nature of a secret agreement.
From conspiration + -al (adjective suffix). This forms an adjective from the noun, describing things that involve or resemble a conspiracy.
This word is quite rare compared to 'conspiratorial'—both mean nearly the same thing, but 'conspiratorial' has become the standard form in English while 'conspirational' faded into relative obscurity.
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