the North American date-plum, a tree common in the U.S. South, 1610s, from Powhatan (Algonquian) pasimenan "fruit dried artificially," from pasimeneu "he dries fruit," containing Proto-Algonquian */-min-/ "fruit, berry."
"the thrill of an unexpected glimpse of something erotically suggestive that is normally hidden," by 2001, from Japanese, from chirari "a glance, a glimpse" + English -ism. The sense extension in Japanese to subtly erotic situations and expressions is said to date from the 1950s.
"aware, up-to-date," first recorded 1908 in "Saturday Evening Post," but said to be underworld slang, of unknown origin. Variously said to have been the name of "a fabulous detective who operated in Cincinnati" [Louis E. Jackson and C.R. Hellyer, "A Vocabulary of Criminal Slang," 1914] or a saloonkeeper in Chicago who "never quite understood what was going on ... (but) thought he did" [American Speech, XVI, 154/1]. Taken up by jazz musicians by 1915. With the rise of hip (adj.) by the 1950s, the use of hep ironically became a clue that the speaker was unaware and not up-to-date.