extension
n. countablen. extra time given to finish a task or a new part added to a building to make it bigger. You might ask for an extension on your homework if you are sick.
n. an additional period of time granted beyond a deadline, or a physical addition to an existing structure. Often used in academic and professional contexts to describe the lengthening of a contract or project timeline.
I asked my boss for a two-day extension on the report.
The homeowners decided to build a kitchen extension rather than moving to a larger house.
The university granted an extension to all students affected by the campus-wide power outage, ensuring that no one was unfairly penalised for the technical failure.
From Middle English extensioun, from Old French estension, from Latin extensiō, extensiōnem.
Commonly takes the preposition 'on' when referring to deadlines or 'to' when referring to physical structures.
I need an extension of my deadlineI need an extension on my deadlineWhile 'of' is grammatically possible, 'on' is the standard collocation for time limits in academic and professional English.