Definition of "jejune"

I have often wondered why some late Writers should sensure Tully's Letters for being too naked and jejune, when that to his Friend Lucceius, which the Reader will find in this Collection, is a plain Demonstration to the contrary?

1702, Thomas Brown, Select Epistles or Letters out of M. Tullius Cicero; and the best Roman, Greek and French Authors both Ancient and Modern

This renders the recognition of alternatives a paramount necessity for a logic of discovery, which can no longer dismiss them with a jejune chapter on 'disjunctive propositions'.

1917, Charles Joseph Singer, Studies in the History and Method of Science

He laid the brush aside and, laughing with delight, cried: -Will he come? The jejune Jesuit.

1922, James Joyce, Ulysses

Doubtless, too, both grammarians and philosophers have been aware that it is by no means easy to distinguish even questions, commands, and so on from statements by means of the few and jejune grammatical marks available, such as word order, mood, and the like : though perhaps it has not been usual to dwell on the difficulties which this fact obviously raises.

1955, J.L. Austin, How To Do Things With Words

Gradus had long been a member of all sorts of jejune leftist organizations.

1962, Vladimir Nabokov, Pale Fire

The debates are necessary and, even at their most jejune, not totally without worth.

1969, G. R. Elton, The Practice of History

Sonja (Diane Keaton): That is incredibly jejune. / Boris (Woody Allen): That's jejune? You have the temerity to say that I'm talking to you out of jejunosity? I am one of the most june people in all of the Russias!"

1975, Woody Allen, Love And Death (motion picture)

I went to the cinema not for entertainment, but for cinematography. For it was only by studying the precise rake of extra-long pans, the trajectory of tracking shots and the jejune emotional appeal of the jump-cut, that I could add to the repertoire of my own internal shoots.

1993, Will Self, My Idea of Fun