Adjective jejune has 3 senses
  1. insubstantial, jejune - lacking in nutritive value; "the jejune diets of the very poor"
    Antonym: wholesome (indirect, via unwholesome)
  2. adolescent, jejune, juvenile, puerile - displaying or suggesting a lack of maturity; "adolescent insecurity"; "jejune responses to our problems"; "their behavior was juvenile"; "puerile jokes"
    Antonym: mature (indirect, via immature)
  3. insipid, jejune - lacking interest or significance; "an insipid personality"; "jejune novel"
    Antonym: interesting (indirect, via uninteresting)