Lacking experience due to lack of challenges; untested.(adjective)
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Use "unchallenged" in a sentence
"Therein lies the danger of allowing Bush to continue his term unchallenged, and un-investigated."
"If you allow insurance companies to get by unchallenged from a public plan, they will play nice until health care isn't the hot button issue any more."
"The fact that such a statement went unchallenged is astonishing, and shows how far down the road we are."