open letternoun [ C ]
uk/ˌəʊ.pən ˈlet.ər/us/ˌoʊ.pən ˈlet̬.ɚ/a letter intended to be read by a lot of people, not just the person it is written to:
An open letter to the prime minister, signed by several MPs, appeared in today's papers.
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。