randomly; recklessly; blindly
Example sentences
彼はやたらに故事来歴に詳しいけれど、それが人生の役に立っているのかはなはだ疑問だね。
He has a great storehouse of knowledge about historical details but I seriously doubt that's of any use in life.
上役にやたらにぺこぺこするな。
Don't be subservient to your boss.