The term "moonlighting" refers to the practice of holding a second job or engaging in additional work outside of one's primary employment, usually without the knowledge of the primary employer. This practice is often done to earn extra income, and it typically occurs during the evening or nighttime hours, hence the term "moonlighting."
The term "moonlighting" is derived from the combination of "moon," referring to the natural light of the moon often illuminating the night, and "lighting," suggesting working or being active in the evening hours. The term likely originated in the 1950s, capturing the image of individuals working under the light of the moon.