Hypothetical or imaginary (8)
I believe the answer is:
notional
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">hypothetical</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">imaginary</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that imaginary can be written as notional)</span><br/ ><br/ ></span>
(Other definitions for notional that I've seen before include "Hypothetical, imaginary" , "Unreal" , "Hypothetical, assumed to be correct" , "La Gioconda" , "Existing as theory, not existing in reality" .)