Like 不 (bú), 未 (wèi) is an adverb that confers opposite meaning to the ensuing word. Whereas 不 (bú) means “not”, “not to”, or “not willing to”, 未 (wèi) means “not yet”, “have not” or “did not”, and concerns the incomplete state of an action. 未 (wèi) is a formal way of saying 还没有 (hái méiyǒu) or 还没 (hái méi).
未知 (wèizhī) means unknown. In mathematics, the unknown quantity is called the 未知数(wèizhīshù). This term is also used in common parlance to refer to something unknown and out of one’s control.
Tā de zhèngzh qiántú háishìyīgè wèizhīshù.
The future of his political career is still uncertain.
闻所未闻( wénsuǒwèiwén) is a formal phrase that means “unheard-of”. It’s interesting that, as a verb, 闻(wén) means both to hear and to smell. In everyday speech, we use 闻(wén) for smelling, and 听(tīng) for hearing. Therefore, the casual way to say “never heard of” is: 没听说过(Méi tīngshuō guò).
前所未有 (qiánsuǒwèiyǒu) is a formal phrase that means “unprecedented”. The casual way to say this is: 从来没有过(cónglái méiyǒu guò).
结婚(jiéhūn) means to get married. 已婚(yǐhūn) means being already married. 未婚(wèihūn) means not yet married, or single.
丈夫(zhàngfū) is a husband, and 妻子(qīzi) is a wife. 夫妻(fūqī) means husband and wife. Therefore, being not yet married, the fiancé is called 未婚夫(wèihūnfū), and the fianceé is called 未婚妻(wèihūnqī).
未来(wèilái) means the future, or in the future.
成年(chéngnián) is being grown-up. 成年人(chéngniánrén) refers to an adult. So, 未成年(wèichéngnián) means underaged.
未老先衰(wèilǎoxiānshuāi) is a phrase used to describe a person who seems to be prematurely senile and weak.
未免(wèimiǎn) is a commonly used adverb that means “rather” or “a bit too”.
Nǐ zhèyàng zuò, wèimiǎn tài guòfèn le.
What you did was a bit too much (inappropriate or unkind).
未必 (wèibì) means “not necessarily”.
Zhèyàng zuò, wèibì kěxíng.
Doing it this way may not necessarily work.
昧(mèi), having the sun obscured by the 未 (wèi) character, connotes haziness or concealment. It’s pronounced the same as the character for a younger sister, 妹(mèi).
昧着良心(mèi zhe liángxīn) or 昧心(mèixīn) refers to doing something unscrupulously, or against one’s conscience.
冒昧(màomèi) is being impudent or taking the liberty to do something that may inconvenience someone else.
愚昧(yúmèi) is a word for describing someone as being foolish and ignorant.
暧昧(àimèi) means ambiguous, dubious or shady.