Superlative form of flimsy: most flimsy.(adjective)
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Use "flimsiest" in a sentence
"Of all the campaign promises and declarations you will hear in the next several months, the flimsiest will be the ones containing the assurance that the candidate is taking a "look" -- even the emphatic "hard look" -- at an idea."
"The next day he subtly suggested a shopping spree, he picked out the flimsiest Helmut Lang dresses at Galerie 66 on the Champs Elysees."
"But this FIFA "regulations" argument has to be one of the flimsiest arguments."