Final answer:
The 'irrevocable date' is not a specific date but metaphorically refers to a moment after which a decision cannot be altered.
Step-by-step explanation:
The phrase 'irrevocable date' does not refer to a specific date in history or a fixed time concept in calendars. However, it might be used metaphorically to refer to a point in time after which a decision cannot be changed or reversed. For example, in historical contexts, when a significant event happens, such as the attack on Pearl Harbor on December 7, 1941, which is marked differently due to time zones as December 8 in Japan, the decisions leading to and consequences following that event are considered irrevocable.
Moreover, the use of the term irrevocable in literature or conversations typically underscores a final and unchangeable decision or event. As in the example sentence 'His decision was irreversible,' the word irrevocable highlights that there is no turning back once a certain point in time has passed or a decision has been made.