fill in

/ˈfɪl ɪn/
noun
  1. A person who temporarily takes the place of another; a substitute.
    • The regular teacher is sick, so we have a fill-in today.
    • He worked as a fill-in for the drummer during the tour.
    • The company hired a fill-in while the receptionist was on leave.
  2. Something that serves as a temporary replacement or addition.
    • The article was a fill-in for the missing page in the magazine.
    • They used a cardboard box as a fill-in for the broken drawer.
    • This old chair is just a fill-in until we buy a new one.
What does "fill in" mean? | whatsthatwordmean | whatsthatwordmean