flimsy
Likely to bend or break under pressure; easily damaged; frail, unsubstantial.
Example
“He expected the flimsy structure to collapse at any moment.”
Other meanings
Of clothing: very light and thin.
Of an argument, explanation, etc.: ill-founded, unconvincing, weak; also, unimportant; paltry, trivial.
Where this comes from
This definition is adapted from “flimsy” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.