Hold it as: a one-way door. Something has changed, and there is no path back to how it was — not because nobody tries, but because the way back does not exist.
From the word’s history
Simply ir- (not) + reversible: 'not able to be turned back'. The modern core is the literal sum of its parts.
就是 ir-（不）加上 reversible（可以倒回去的），字面意思「不能被倒回去」。這個字的現代核心跟它的組成完全一致，拆開來看就懂——這也是為什麼學會這個 ir- 前綴，irregular、irrelevant、irresponsible 一起就好認了。
Wiktionary etymology tree supplied in the payload (ir- + reversible)
登入就可以看每一支怎麼連回核心畫面。
原始詞典資料3 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
irreversibleadj/ˌɪr.ɪˈvɜː.sə.bəl/
- 1
Incapable of being reversed or turned about or back; incapable of being made to run backwards.
- an irreversible engine
- 2
Incapable of being reversed, recalled, repealed, or annulled.
- an irreversible sentence or decree
- Manganism has been known about since the 19th century, when miners exposed to ores containing manganese[…]began to totter, slur their speech and behave like someone inebriated. The poisoning was irreversible, and soon ended in psychosis and death.
- 3
natural-sciencesphysical-sciencesphysicsIncapable of being reversed to the original state without consumption of free energy and increase of entropy.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。