Superlative form of clumsy: most clumsy.(adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "clumsiest" in a sentence
"Find the meaning of your gestures by all means (though why the clumsiest should be preferred I do not understand — I have in mind some manger scenes) and if you can bring yourself to at this particular season of the year, decorate, feast and give; manifest a bit of cheer even if nobody asks you why."
"IF A breeder should stock his farm with the swiftest race horses obtainable, and employ a method of selection whereby only the slowest and clumsiest horses were bred, it would not be many generations before he would have a breed of very slow and very clumsy horses."
"- But, with his hand, he is certainly the clumsiest creature living."