unheard-of

adj not previously known of or done; unprecedented 前所未闻的; 无先例的; 空前的: Radiation reached unheard-of levels. 辐射作用已达到前所未有的程度. * It was unheard-of for anyone to complain. 从未听说过有人投诉的事.

unglazed, ungodly, ungovernable, ungracious, ungraciously, ungrammatical, ungrammatically, ungrateful, ungratefully, ungrudging, unguarded, unguent, unguided, unhappily, unhappiness, unhappy, unhealthily, unhealthiness, unhealthy, unheard, unheroic, unhesitating, unhinge, unholiness, unholy, unhoped-for, unhorse, unhurt, uni-, UNICEF, unicellular, unicorn, unidentified, unidimensional, unidirectionally, unification, unified, uniform, uniformed, uniformity,