Jejune (j-jn): Dry, dull, uninteresting, insipid. From Latin iinus (dry, meager, fasting).
There are a couple of English words whose meaning I invariably have to look up no matter how many times I've done so in the past. Jejune is one. (Heuristics is another, but I think I've finally nailed that one.) To my ear, it sounds like French, so I trip myself up thinking it has something to do with youth (jeunesse) or the color yellow (jaune).¹ Or I think it sounds like juicy. Or like that thing Carson Kressley used to do with sleeves on Queer Eye for the Straight Guy: "We'll just jejune them a little..."
It turns out I'm not the only one nonplussed by jejune. In Alphabet Juice, a selective and highly entertaining romp through the alphabet, Roy Blount Jr. introduces the letter J with a list of jolly words: jump, joy, jet, jig, jingle, jiffy. Sure, there are "downer words" that begin with J, he adds, but they all bristle with energy: jerk, jeer, jail, jihad. He continues:
Let me importune ya
Not to be jejune, ya
I'm planning to buy Alphabet Juice, but in the meantime I've been listening to a library copy of the audiobook, read by the author in his delicious Georgia drawl. (Drawl is one of the words Blount ruminates on in Alphabet Juice.) As a listening experience, it's anything but jejune.
¹ Webster's New World College Dictionary (2009) says the "childish" definition comes from "confusion with 'juvenile.'" The Online Etymology Dictionary gives only "dull in the mind, flat, insipid," and traces the word's entry into English back to 1615.