If something that has happened was unforeseen, it was not expected to happen or known about beforehand.
近义词
surprising , unpredicted , unexpected
反义词
foreseen , predicted , expected
双语例句
例： Radiation may damage cells in a way that was previously unforeseen.
辐射也许会以以前未能预见的方式损坏细胞。
例： Unfortunately, due to unforeseen circumstances, this year's show has been cancelled.
遗憾的是，由于意外情况，今年的演出已被取消了。
例： Barring any unforeseen circumstances, interest rates should remain relatively stable in the medium term.
没有任何意外情况的话，利率在中期应保持相对稳定。