The antonyms for "underwrite" include abandon, disapprove, disavow, discourage, oppose, reject, and withdraw. Underwriting refers to the act of providing financial support or guarantees for a project or venture. Antonyms for "underwrite" suggest withholding financial or moral support, disapproving or opposing a proposal, or withdrawing from a commitment. For example, if a company decides to disapprove a proposal for a new business venture, they may withdraw their financial support and oppose further development of the project. Similarly, if an insurance company decides to reject an underwriting application, they would not provide coverage for that policy.