When it's time to get serious and focus on a task, we often say it's time to knuckle down. But what other expressions can we use to convey the same meaning? Some synonyms for knuckle down include buckle down, hunker down, dig in, get down to business, concentrate, and apply oneself. Essentially, all of these phrases suggest a need to concentrate and work hard in order to achieve a goal. Whether you're studying for an exam, starting a new project, or simply trying to reach a personal goal, using any of these alternatives for knuckle down can help you motivate yourself and stay focused on the task at hand.