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wholly; solely; entirely; exclusively; devotedly; fixedly
principally; mostly; chiefly; mainly
最近の彼はもっぱら読書に時間を費やしているらしい。
Recently, he seems to be devoting his time exclusively to reading.
退職後はもっぱら庭の手入れを楽しみにして暮らす。
After retirement, I live looking forward exclusively to tending the garden.
彼女の関心はもっぱら環境問題に向けられているようだ。
Her interest seems to be directed exclusively toward environmental issues.