The French term for boredom, ennui, is sometimes used in English as well, at least since 1778. The term ennui was first used "as a French word in English;" in the 1660s and it was "nativized by 1758".[7] The term ennui comes "from French ennui, from Old French enui "annoyance" (13c.), [a] back-formation from enoiier, anuier.[7] "The German word for "boredom" expresses this: Langeweile, a compound made of lange "long" and Weile "while", which is in line with the common perception that when one is bored, time passes "tortuously" slowly.[8]
Thomas Goetz, the lead researcher of the work and a professor at the University of Konstanz in Germany, says the multiple types of boredom can be loosely characterized along two dimensions. First, whether it is associated with a positive (score of 1) or negative (score of 5) emotion, and second, by degree of arousal, from calm (score of 1) to fidgety (score of 5).

The highest levels of arousal and negative emotions. A person in a reactant boredom state has a strong motivation to escape his or her boring situation and avoid those responsible for it (such as teachers or a boss). Reflects significant restlessness and aggression. There are persistent thoughts about specific, “more highly valued alternative situations.”

"Meh" is an interjection used as an expression of indifference or boredom. It may also mean "be it as it may".[40] It is often regarded as a verbal shrug of the shoulders. The use of the term "meh" shows that the speaker is apathetic, uninterested, or indifferent to the question or subject at hand. It is occasionally used as an adjective, meaning something is mediocre or unremarkable.[41]

Although it has not been widely studied, research on boredom suggests that boredom is a major factor impacting diverse areas of a person's life. People ranked low on a boredom-proneness scale were found to have better performance in a wide variety of aspects of their lives, including career, education, and autonomy.[30] Boredom can be a symptom of clinical depression. Boredom can be a form of learned helplessness, a phenomenon closely related to depression. Some philosophies of parenting propose that if children are raised in an environment devoid of stimuli, and are not allowed or encouraged to interact with their environment, they will fail to develop the mental capacities to do so.
When the antiproton was discovered … it sent a wave of ennui through the physics community. Not that its discovery was unimportant, but on the basis of Dirac's theory, everybody expected it. — Roger G. Newton, The Truth of Science, 1997 Chauncey and I were keen enough about our aesthetic solution to the ennui of war to try to proselytize others. He organized discussion groups with the crew; I took volunteers to visit landmarks … — Louis Auchincloss, "Atlantic War," in Authors at Sea, ed. Robert Shenk,  1997 The attendant outside was standing on tennis balls, exercising the soles of her feet, her body swaying back and forth with the ennui of jelly. — Edna O'Brien, New Yorker, 17 June 1991 Thus the days of life are consumed, one by one, without an object beyond the present moment; ever flying from the ennui of that, yet carrying it with us … — Thomas Jefferson, in a letter dated 7 Feb. 1787 Thomas Jefferson: Writings,  1984 the kind of ennui that comes from having too much time on one's hands and too little will to find something productive to do