Bloomsday
/ˈbluːmzdeɪ/(also Bloom's day)
noun
The 16th of June 1904. Also: the 16th of June of any year, on which celebrations take place, especially in Ireland, to mark the anniversary of the events in Joyce's Ulysses.
Origin
1920s; earliest use found in James Joyce (1882–1941), writer. From the genitive of the name of Leopold Bloom, one of the central characters in James Joyce's novel Ulysses, in which all the action takes place on one day, 16 June 1904 + day, probably punningly after doomsday.