日曆上真的會移動的那一天
字面的一層，也是畫面的出處：日期是算出來的，不是印好的。
noun · C1
A religious festival, such as Easter, whose date is worked out by a set of rules rather than fixed on the calendar, so it falls on a different day each year.
日期不固定的節日
核心畫面
Think of a calendar with most of its holidays nailed down — the same square every year — and one that refuses to stay still. Its day is not written on the calendar at all; it is worked out from a rule, so each year it lands somewhere new and you have to look it up again. That one loose day is the picture. Both uses on this page are that day: first the real festival, then anything else in life whose time will not sit still, so you check again every week to find out when it is.
可以想成一本日曆：大部分的節日都被釘死在同一格，年年不動，只有一個不肯待著。它的日子根本沒印在日曆上，而是按一套規則…更多收起
可以想成一本日曆：大部分的節日都被釘死在同一格，年年不動，只有一個不肯待著。它的日子根本沒印在日曆上，而是按一套規則算出來的，所以每年都落在新的地方，你每次都得重查一次。那一格鬆動的日子就是這個詞的畫面。這一頁的兩個意思都是那格日子——先是真正的節日，接著是生活裡任何時間定不下來、每週都得再確認一次的事。Two branches
生活裡定不下來的時間
把那格鬆動的日子搬進日常：節日換成任何一件事，規則換成沒有規則。
noun · C1
Something that does not happen at a fixed time, so the day or the hour keeps changing and you can never be sure when it will be.
時間不固定的事