sill [sills](base of a window) noun [UK: sɪl] [US: ˈsɪl]
windowsill(the horizontal member protruding from the base of a window frame) noun [UK: ˈwɪn.dəʊ.sɪl] [US: ˈwɪndo.ʊ.sɪl]There's a sparrow on the windowsill. = Hay un gorrión en el alféizar de la ventana.