de
de — 字首
1. A prefix that you add to the beginning of a verb or noun to give it the opposite
反；除去；減
加在動詞或名詞前，表示相反、去除或減少
A prefix that you add to the beginning of a verb or noun to give it the opposite meaning, or to show that something is taken away, removed, or made smaller.
The company decided to deactivate the old security system after the upgrade.
升級後，公司決定解除啟用舊的安全系統。
de- + activate → deactivate (reverse action)
Large areas of forest near Kyoto have been deforested to build new roads and houses.
京都附近的大片森林遭到砍伐，用來蓋新的道路和房屋。
de- + forest → deforest (remove trees)
Ambassador Kwame took steps to de-escalate the tension between the two nations.
Kwame 大使採取步驟，緩和兩國之間的緊張局勢。
Programmer Elena spent the whole afternoon debugging the code before the launch.
程式設計師 Elena 花了整個下午除錯程式碼，準備上線。
General Omar agreed to declassify the old military records after thirty years.
Omar 將軍同意在三十年後解密這些舊軍事紀錄。
- un-
The most common reversal prefix in English; attaches to a wider range of words than de- (e.g., undo, unpack, unwrap). De- tends to sound more formal or technical.
- dis-
Also adds opposite or negative meaning, but often carries a sense of 'apart' or 'away' (e.g., disagree, disconnect, disapprove). Less about removal and more about negation or separation.
- anti-
Means 'against' rather than 'reverse' or 'remove' (e.g., anti-war, anti-virus). Used with nouns and adjectives, not typically with verbs.
- re-
Means 'again' or 'back' — the opposite direction from de- (e.g., activate → deactivate / reactivate; classify → declassify / reclassify). Re- restores or repeats; de- reverses or removes.
文法句型
de- + [verb] — forms a verb with opposite or removal meaning
de- + [noun] — forms a noun meaning removal or reduction of something
用法筆記
This prefix has three main jobs: (1) reversing an action (deactivate, declassify, defrost); (2) removing something (debug, deforest, de-ice, decontaminate); (3) reducing or lowering (de-escalate, devalue, downgrade is less common, but de-emphasize works). The prefix attaches most naturally to verbs and nouns that come from Latin or French roots. Avoid inventing new de- words — check a dictionary first, as not every verb or noun accepts this prefix.