retroreflection

/ˌrɛtroʊrɪˈflɛkʃən/
noun
  1. The reflection of light back toward its source, especially from a surface designed to do this.
    • Safety vests rely on retroreflection to make workers stand out in low light.
    • The retroreflection from the road signs makes them visible at night when headlights shine on them.
    • Bicycle reflectors use retroreflection to help drivers see cyclists in the dark.