flood-gate (n.)youdaoicibaDictYouDict[flood-gate 词源字典]
early 13c. in the figurative sense "opportunity for a great venting" (especially with reference to tears or rain); literal sense is mid-15c. (gate designed to let water in or keep it out as desired, especially the lower gate of a lock); from flood (n.) + gate (n.).[flood-gate etymology, flood-gate origin, 英语词源]