sill 
/ˈsɪl/ noun
plural sills /ˈsɪl/ noun [count] 1 a : the shelf at the bottom of a window frame : windowsill — see picture at window
b : a piece of wood, metal, or stone at the bottom of a door frame 2 : the part of the frame of a car that is directly under its doors
b : a piece of wood, metal, or stone at the bottom of a door frame
