Comparative form of clumsy: more clumsy(adjective)
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Use "clumsier" in a sentence
"And I found they make it clumsier to hold the iPad for reading."
"That produced new, clumsier line breaks and spacing and, with long speeches, larger balloons."
"Many apps on the phone aren't as polished or powerful as typical PC apps, and I found them clumsier to use with the keyboard and touch pad, as opposed to the touch screen for which they were designed."