There are a number of synonyms for the term "second job", each with its own connotations and nuances. One common synonym is "moonlighting", which typically refers to taking on additional work outside of regular employment hours. Another similar term is "side hustle", which can refer to any extra work done to earn money on the side. "Freelancing" is a synonym that often implies working on a project-by-project basis, rather than holding down a regular job. "Gigging" is a term that has gained popularity in recent years to refer to short-term, contract-based work. Finally, "part-time job" is a straightforward synonym that simply refers to any job taken on in addition to one's primary employment.