The term SILL refers to a structural element found in buildings. It is typically a flat piece of material, such as wood or stone, that is placed at the bottom of a window or door frame. The term SILL can also refer to a horizontal beam or lintel that supports the weight of a wall or roof. The crossword solutions for the term SILL are THRESHOLD (9 letters), SHELF (5 letters), and LEDGE (5 letters). A THRESHOLD is a raised sill that serves as a barrier between two spaces, such as a doorway or window. A SHELF is a flat surface that is used to store items and is usually attached to a wall. A LEDGE is a narrow SHELF or strip of material that projects from a wall or other structure.