The phrase "box off" refers to completing a task or finishing something satisfactorily. Some synonyms for this phrase include "wrap up," "conclude," "complete," "finish," "finalize," "seal," or "terminate." These words all refer to the act of bringing something to a close or achieving a goal. Each term can be used in various contexts, from the completion of a project at work to finishing a personal task, like packing for a trip. Using these synonyms adds variety to the language and can help to avoid repetitiveness when writing or speaking. Ultimately, the choice of synonym depends on the context and tone you want to convey.