“+ adjective
Etymology: Middle English, from un- (I) + substantial
: not substantial: as
a. : lacking a basis in fact
an unsubstantial argument
an unsubstantial hope
unsubstantial speculation
b. : not having matter or substance : visionary , unreal
an unsubstantial phantom … luring men away from safety and ease — Bertrand Russell
remote and unsubstantial as the most distant nebulae — G.W.Russell
pale and unsubstantial in the moonlight, the shadowy figure of a man was moving — C.B.Nordhoff & J.N.Hall
c. : lacking firmness or strength in construction : weak , unstable
a chipping sparrow … collecting stray hairs from the farm horses' tails for lining her very unsubstantial nest — W.P.Smith
a child of wax, delicate and charming and unsubstantial — H.G.Wells
birds and butterflies and such unsubstantial things — W.H.Hudson †1922
• un·substantially “+ adverb