rainbow rainbow /ˈreɪnˌboʊ/

noun

1. () An arc of colored light in the sky caused by refraction of the sun's rays by rain  ( rainbow )
   an arc of colored light in the sky caused by refraction of the sun's rays by rain
    The rainbow was a beautiful sight, with its vibrant colors arching across the sky
   The rainbow was a beautiful sight, with its vibrant colors arching across the sky
   
   
2. An illusory hope  ( rainbow )
   an illusory hope
    Chasing rainbows
   chasing rainbows