Simple past tense and past participle of stun.(verb)
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Use "stunned" in a sentence
"The Bulldogs began to pull away early in the second half, taking a 55-45 lead on Marquise Carter's 3-pointer that had a Saint Mary's crowd that came to toast a title stunned and silent - if only briefly."
"Dvorak turned and looked at them, his expression stunned."
"To say that the United States was stunned is but to expose the inadequacy of language."