Valmiki Ramayana Kishkindha Kanda Sarga 23 Shloka 12

या नारी any woman, पतिहीना without husband, पुत्रिणी mother of sons, भवतु कामम् even so, धनधान्यैस्सुपूर्णाऽपि a prosperous lady with wealth and grain in abundance, बुधैः by learned people, विधवेति only a widow, उच्यते is called so.

'Even if a woman without husband, is blessed with sons and abundant wealth and grain, still learned people call her a widow.