to give permission for something to happen:
a traffic signal with the green part lit as a signal that it is safe to go:
fig. A green light is also permission to do something:
permission to start doing something:
to give permission for someone to do something or for something to happen:
英语词典包含110679条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。