Hypothetical (8)
'hypothetical' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for notional that I've seen before include "Theoretical" , "Assumed to be correct for particular purpose, say estimate" , "Existing as theory, not existing in reality" , "Theoretic" , "Imaginary - in on a lot (anag)" .)
'hypothetical' is the definition.
(I know that hypothetical can be written as conjectural)
This is all the clue.
(Other definitions for conjectural that I've seen before include "Involving guesswork" , "Hypothetical, surmised" , "Like guesswork" .)
'hypothetical' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for theoretic that I've seen before include "impractical" , "purely speculative" , "Not practical" .)