Vast/væst/ Definition 1 of 2Pro Tip 1/3Physical Spaces Often describes places with wide, unbroken areas without many details. They traveled across the vast plains. Pro Tip 2/3Not Detailed Use 'vast' to speak about something overall, without focusing on specifics. The vast collection included countless items. Pro Tip 3/3Overwhelming Quantity Implies a quantity that is hard to comprehend or manage. She faced a vast array of choices.