also date-line, 1880 as an imaginary line down the Pacific Ocean on which the calendar day begins and ends, from date (n.1) + line (n.). Never set by any treaty or international organization, it is an informal construct meant to coincide with a line 180 degrees (12 hours) from Greenwich, but it always has followed a more or less crooked course.
Meaning "line of text that tells the date and place of origin of a newspaper, article, telegram, etc." is by 1888.
imaginary earthly paradise, by 1938, from Shangri-La, name of Tibetan utopia in James Hilton's novel "Lost Horizon" (1933, film version 1937). In Tibetan, la means "mountain pass."
also materialisation, 1822, "act of investing with or assuming a material form; a change from a spiritual, ideal, or imaginary state to a state of matter," noun of action from materialize. In spiritualism, "the assumption (by a spirit) of a bodily form," by 1875.