adv. Usage Problem.
USAGE NOTE Bad is often used as an adverb in sentences such as The house was shaken up pretty bad or We need water bad. This usage is common in informal speech but is widely regarded as unacceptable in formal writing. In an earlier survey, the sentence His tooth ached so bad he could not sleep was unacceptable to 92 percent of the Usage Panel. •
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The colloquial use of "bad" as an adverb is okay with me despite what the usage panel says. It wouldn't surprise me if some members of the usage panel actually use "bad" as an adverb in real life.
Student or Learner