early 15c., "not in accord with physical nature," from un- (1) "not" + natural (adj.). Meaning "artificial" is attested from 1746; that of "at variance with moral standards" is from 1520s. Related: Unnaturally; unnaturalness.
权威例句
1. She gave him a bright, determined smile which seemed unnatural.
她对他开朗、坚定地一笑,但笑得有点不自然。
2. I consider activities such as jogging and weightlifting as unnatural.
我认为像慢跑、举重这样的运动不符合自然规律。
3. The aircraft rose with unnatural speed on take-off.
那架飞机以反常的速度起飞升空。
4. The altered landscape looks unnatural and weird.
改造后的景观看起来很不自然,极其怪异。
5. It seems unnatural for a child to spend so much time alone.