theories about the extinction of dinosaurs are still highly conjectural.
Examples of conjectural
conjectural
I often say conjectural things in the discussion I wouldn't say in the article.
From the en.wikipedia.org
Such theories, like the more specific electoral ones, can only be conjectural.
From the economist.com
The design of the earliest oared vessels is mostly unknown and highly conjectural.
From the en.wikipedia.org
The Kim paper is hypothetical conjecture regarding a field of conjectural science.
From the en.wikipedia.org
You gave no references, and everything you said was conjectural or incomprehensible.
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What is known about the tactics of the Imperial Era is largely conjectural.
From the en.wikipedia.org
The scanty evidence makes explaining these differences largely conjectural.
From the en.wikipedia.org
Ashton also includes a conjectural map of Cantre'r Gwaelod within the bay.
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Attribution is conjectural but probable, as Arta was the capital of Epirus.
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More examples
Based primarily on surmise rather than adequate evidence; "theories about the extinction of dinosaurs are still highly conjectural"; "the supposed reason for his absence"; "suppositious reconstructions of dead languages"; "hypothetical situation"
(conjecturally) in a manner involving or inclined to conjecture and supposition
A conjecture is a proposition that is unproven but appears correct and has not been disproven. Karl Popper pioneered the use of the term "conjecture" in scientific philosophy. ...