The phrase "get down to work" is often used to signify the beginning of a task or assignment. However, there are a variety of synonyms that can be used to convey the same meaning in different contexts. Some examples of synonyms for "get down to work" include "begin the task," "start the project," "engage in the work," and "start the job." Other expressions that can be used in place of "get down to work" include "roll up your sleeves," "tackle the task," "get serious," and "put your nose to the grindstone." The specific synonym chosen will depend on the speaker's tone, the context, and the intended audience.