Definition of "discontent"

Another source of discontent with the Phase I stock has been obviated by relocation of the interior heating elements and the introduction of thermostatic control; this has eradicated the searing blasts of hot air passengers used to feel about their calves [...].

1961 February, “Talking of Trains: Phase II units in service”, in Trains Illustrated, page 69

Now is the winter of our diſcontent, / Made glorious ſummer by this ſonne of Yorke: / And all the cloudes that lowrd vpon our houſe, / In the deepe boſome of the Ocean buried.

c. 1593 (date written), [William Shakespeare], The Tragedy of King Richard the Third. […] (First Quarto), London: […] Valentine Sims [and Peter Short] for Andrew Wise, […], published 1597, [Act I, scene i]

Spring was moving in the air above and in the earth below and around him, penetrating even his dark and lowly little house with its spirit of divine discontent and longing.

1908, Kenneth Grahame, The Wind in the Willows, New York: Charles Scribner's Sons, page 1

[...] Paſſion seemed to be much diſcontent, but Patience was very quiet. Then Chriſtian aſked, What is the reaſon of the diſcontent of Paſſion.

1678, John Bunyan, The Pilgrim’s Progress from This World, to That which is to Come: […], London: […] Nath[aniel] Ponder […]; reprinted in The Pilgrim’s Progress (The Noel Douglas Replicas), London: Noel Douglas, […], 1928, page 22