1. not seen or observed by anyone; having no witnesses

Examples

• The accident occurred on a remote road and went unwitnessed for hours.
• Her act of kindness was unwitnessed but deeply meaningful.
• The crime remained unwitnessed despite happening in broad daylight.
• He preferred his charitable donations to remain unwitnessed.
• The unwitnessed event left investigators with few clues.
• Many heroic deeds go unwitnessed and unrecognized.