insubstantiality

nouns

lack of solid substance and strength

is derived from

is a type of (narrower)

the property of lacking physical or mental strength; liability to failure under pressure or stress or strain

"his weakness increased as he became older"; "the weakness of the span was overlooked until it collapsed"

lacking substance or reality

is derived from

antonym

is a type of (narrower)

the quality of not being physical; not consisting of matter