qualm(noun): an uneasy feeling of doubt, worry, or fear, especially about one's own conduct; a misgiving.

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juggernaut(noun): a huge, powerful, and overwhelming force.

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clumsy(adjective): difficult to handle or use; unwieldy.

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unimpeachable(adjective): not able to be doubted, questioned, or criticized; entirely trustworthy.

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trifling(adjective): not worth considering.

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I hope this helps you if you are preparing for GRE exams.