› disapproving a writer, especially a journalist, who produces articles, books, etc. that are of low quality: a media/newspaper hack
› disapproving someone who works mainly for money without worrying about beliefs or the opinions of others: a political/party hack
› US informal a person who drives a taxi
› IT an illegal use of a computer to access information stored on another computer system or to spread a computer virus : A hack into an employee's email provided access to a number of confidential documents.