In conventional usage, boredom is an emotional and occasionally psychological state experienced when an individual is left without anything in particular to do, is not interested in their surroundings, or feels that a day or period is dull or tedious. It is also understood by scholars as a modern phenomenon which has a cultural dimension. "There is no universally accepted definition of boredom. But whatever it is, researchers argue, it is not simply another name for depression or apathy. It seems to be a specific mental state that people find unpleasant—a lack of stimulation that leaves them craving relief, with a host of behavioural, medical and social consequences."[1] According to BBC News, boredom "...can be a dangerous and disruptive state of mind that damages your health"; yet research "...suggest[s] that without boredom we couldn't achieve our creative feats."[2]
Boreout is a management theory that posits that lack of work, boredom, and consequent lack of satisfaction are a common malaise affecting individuals working in modern organizations, especially in office-based white collar jobs. This theory was first expounded in 2007 in Diagnose Boreout, a book by Peter Werder and Philippe Rothlin, two Swiss business consultants. They claim the absence of meaningful tasks, rather than the presence of stress, is many workers' chief problem.
The bored antihero became prominent in early 20th century existentialist works such as Franz Kafka's The Metamorphosis (1915),[43] Jean-Paul Sartre's La Nausée (1938) (French for 'Nausea'),[44] and Albert Camus' L'Étranger (1942) (French for 'The Stranger').[45] The protagonist in these works is an indecisive central character who drifts through his life and is marked by ennui, angst, and alienation.[46]
Boredom also plays a role in existentialist thought. Søren Kierkegaard and Friedrich Nietzsche were two of the first philosophers considered fundamental to the existentialist movement. Like Pascal, they were interested in people's quiet struggle with the apparent meaninglessness of life and the use of diversion to escape from boredom. Kierkegaard's Either/Or describes the rotation method, a method used by higher level aesthetes in order to avoid boredom. The method is an essential hedonistic aspect of the aesthetic way of life. For the aesthete, one constantly changes what one is doing in order to maximize the enjoyment and pleasure derived from each activity.

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.

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]

Boredom is similar to mental fatigue and is caused by repetition and lack of interest in the details of our tasks (such as tasks that require continuous attention, waiting at the airport, prisoners locked in cells). Any experience that is predictable and repetitive becomes boring. In general, too much of the same thing and too little stimulation can cause in its victim an absence of desire and a feeling of entrapment (Toohey, 2012).