[ after verb ] not familiar with something, or not used to something不习惯的;不适应的
The weather presented a particular challenge, especially for soldiers unaccustomed to subarctic conditions.这种天气尤其对不适应亚北极地区气候的军人提出了特别的挑战。
[ before noun ] not usual不寻常的
The Olympic and world champion finished in the unaccustomed position of fourth.这位奥运会冠军和世界冠军表现失常,最后仅仅获得了第4名。