Tenuousness is a word that refers to a lack of substance or strength, and there are several synonyms that can be used to convey the meaning in different ways. One such synonym is fragility, which suggests something that is delicate and easily breakable. Another synonym is flimsiness, which implies something that is thin and insubstantial. Weakness is another term that can be used to describe tenuousness, highlighting a lack of robustness or resilience. Finally, the word instability captures the sense of something that is shaky or uncertain, and prone to collapse or crumble. All of these words can be used interchangeably with tenuousness to evoke a sense of frailty or uncertainty.