Jejune means devoid of significance or interest. Jejune suggests a lack of rewarding or satisfying substance (ex. a jejune and gassy speech).

Another jejune definition: JUVENILE, PUERILE (ex. jejune reflections on life and art). Jejune is also synonymous with the words insipid, vapid, flat, banal and inane.

Insipid - implies a lack of sufficient taste or savor to please or interest
(ex. an insipid romance with platitudes on every page)

Vapid - suggests a lack of liveliness, force, or spirit
(ex. an exciting story given a vapid treatment)

Flat - applies to things that have lost their sparkle or zest
(ex. Although well-regarded in its day, the novel now seems flat.)

Banal - stresses the complete absence of freshness, novelty, or immediacy
(ex. a banal tale of unrequited love)

Inane - implies a lack of any significant or convincing quality
(ex. an inane interpretation of the play)