"Buckled down" is a common idiom used to describe someone who is working hard and focusing on a particular task. However, there are several other synonyms that can be used to convey a similar meaning. Some of these include knuckling down, getting down to business, laying the groundwork, getting serious, putting in the effort, and rolling up one's sleeves. Each of these phrases captures the essence of buckling down and emphasizes the idea of putting in the necessary work to achieve a specific goal. Whether you are preparing for an exam, working on a project, or striving to meet a deadline, using these synonyms can help you communicate your determination and commitment to hard work.