un-
pref 前缀
1 (with adjs, advs and ns 与形容词、 副词和名词结合) not 不; 非: unable
unconsciously * untruth.2
(a) (with vs forming vs 与动词结合构成动词) reverse or opposite of 相反; 对立: unlock
undo.
(b) (withns forming vs 与名词结合构成动词) remove from or deprive of 移走; 免去: unearth
unmask * unhorse. un-, NOTE ON USAGE 用法
Compare the negative prefixes non-, un-, dis- and a-. 试比较含否定意义的前缀n on-、un-、 dis-、 a-.
1 Non- and un- are the most freelyadded prefixes. *non-和un-在使用上最为自由. Non-is used with nouns, adjectives and adverbs and indicates an absence of something *non-附加在名词、 形容词、 副词前, 表示没有或不存在某事物
a non-drinker 不喝酒的人
a non-stick pan 不粘底的锅
speaking non-stop说个不停. Un- is added to adjectives and indicates the opposite quality from the simple word *un-附加在形容词前, 表示与原词相反的意义
unexpected = `surprising'（没有料到的）
unwise = `foolish' （愚蠢的）. Compare non-British (`of a nationality which is not British') andun-British (`being disloyal to Britain'). 试比较non-British（非英国籍的）和un-British（不忠於英国的）.
2 In- is used with fewer words than un-, also to form opposites. *in-也用以构成反义词, 但能与之结合的词较un-少些. There are variant spellings 这一前缀有几种拼写形式
il- before l (illogical); im- before b, m, p (imbalance, immaterial, impossible) and ir- before r (irresponsible).*il-用於l之前（illogical）; im-用於b、 m、 p之前（imbalance、 immaterial、 impossible）; ir-用於r之前（irresponsible）.
3 Dis- is also used with verbs, adjectives and nouns to form opposites *dis-亦用於动词、 形容词、 名词之前, 构成反义词: dislike 不喜欢
disobedient 不服从的 * distrust 不信任.
4 A- is mostly used in formal or technical words to indicate `lacking in' or `lack of' *a-主要用在较文的词或科技词之前, 表示｀缺乏＇或｀无＇
amorphous (`lacking in shape') 无定形的
anarchy (`lack of rule') 无政府状态.
5 It is not possible to predict whether un-, in- or dis- is used with a particular word and the correct form must be noted and learned 一个词的前缀究竟是用un-、 in-还是dis-是没有固定规律可循的, 只好留心逐一记住.