undersill

English

Etymology

under- +‎ sill

Adjective

undersill (not comparable)

1. Beneath a sill.
   • 1975, Robert Scharff, The complete book of home remodeling, page 292:

     A vinyl undersill trim or finish trim should be used under windowsills to receive the cut edges of the siding.

Noun

undersill (plural undersills)

1. A sill placed underneath something.