burn the midnight oil

Definition

To work studiously, especially late into the night.

Etymology

Originally referring to the act of burning lamp oil in oil lamps for light at night. The collocation midnight oil in its literal sense is attested from mid 17th c.

Example Sentences

• "Near-synonym: pull an all-nighter"
• "He was burning the midnight oil to finish his paper."
• "She was burning the midnight oil to finish her part of the project."