jejune (adj.)

1610s, "dull in the mind, flat, insipid, wanting in interest," from Latin ieiunus "empty, dry, barren," literally "fasting, hungry," a word of obscure origin. De Vaan finds it to be from a PIE root meaning "to worship, reverence," hence "to sacrifice" (with cognates including Sanskrit yajati "to honor, worship, sacrifice," Avestan yaza- "to worship," Greek agios, agnos "holy;" see hagio-), and writes that the Latin word and its relatives "would be based on the habit to perform the first sacrifice of the day on an empty stomach." Related: jejunal; jejunally.