noun
lap
LAP/læp/
The upper surface of a seated person's thighs.
The book rests on the seated woman's lap.

Etymology
The garment flap came to mean the lower front of a shirt or skirt, then the seated person’s upper legs beneath it. The word’s deeper origin is uncertain.
In context
ask you to sit down before taking your seat however if no instruction is given wait for the interviewer to be seated and then sit put your napkin on your lap once everyone is seated
More examples
- She rests an open book on her lap.
- The child climbs into his father's lap.
- We spread napkins across our laps before eating.
Forms
lap · laps