apathetic(adjective): showing or feeling no interest, enthusiasm, or concern.

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vociferous(verb) :conspicuosly and offensively loud

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diffident(adjective): modest or shy because of a lack of self-confidence.

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cryptic(adjective): having a meaning that is mysterious or obscure.

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audacious(adjective): showing a willingness to take surprisingly bold risks.

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