/ʌnˈpresɪˌdentɪd/ adj.1.(that has never happened before)无前例的
In 1987 the Socialists took the unprecedented step of appointing a civilian to command the force.1987年, 社会党人史无前例地任命了一位文职人员来指挥军队。
not unprecedented不是没有先例的
Such a move is rare, but not unprecedented.这样的举动是罕见的, 但并非没有先例。
2.(very great)无比的；空前的
Then came a period of unprecedented wealth and prosperity.然后出现了一段空前的富裕和繁荣时期。
unprecedented success空前的成功
The scheme has been hailed as an unprecedented success.这个方案被誉为是一个空前的成功。