He explained the proposal insubstantially, leaving the committee with more questions than answers.

Her argument sounded insubstantial when the professor asked for evidence.

The critic argued that the film's insubstantiality undermined its emotional impact.

Despite her careful explanations, the committee dismissed his concerns as mere insubstantialities.

The committee dismissed the insubstantiated claims after reviewing the evidence.

The historian dismissed the insubstantiable rumor as unworthy of further study.