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]
“When I have neither pleasure nor pain and have been breathing for a while the lukewarm insipid air of these so called good and tolerable days, I feel so bad in my childish soul that I smash my moldering lyre of thanksgiving in the face of the slumbering god of contentment and would rather feel the very devil burn in me than this warmth of a well-heated room. A wild longing for strong emotions and sensations seethes in me, a rage against this toneless, flat, normal and sterile life. I have a mad impulse to smash something, a warehouse, perhaps, or a cathedral, or myself, to commit outrages, to pull off the wigs of a few revered idols...”
“Boredom – the psychological state that we experience whenever we are uninterested in what we are currently doing – is one of the defining traits of humanity. Time is the psychological nemesis of humankind. Tedium, a fundamental angst of humankind, arises from human beings’ ability to perceive time and our attempts to derive meaning from our personal existence.”

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 a condition characterized by perception of one's environment as dull, tedious, and lacking in stimulation. This can result from leisure and a lack of aesthetic interests. Labor and art may be alienated and passive, or immersed in tedium. There is an inherent anxiety in boredom; people will expend considerable effort to prevent or remedy it, yet in many circumstances, it is accepted as suffering to be endured. Common passive ways to escape boredom are to sleep or to think creative thoughts (daydream). Typical active solutions consist in an intentional activity of some sort, often something new, as familiarity and repetition lead to the tedious.

In contexts where one is confined, spatially or otherwise, boredom may be met with various religious activities, not because religion would want to associate itself with tedium, but rather, partly because boredom may be taken as the essential human condition, to which God, wisdom, or morality are the ultimate answers. Many existentialist philosophers, like Arthur Schopenhauer, espouse this view. This view of religiosity among boredom does affect how often people are bored. People who had a higher religiosity while performing boring task, reported less boredom than people of less religiosity. People performing the meaningless task had to search less for meaning.[24]

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.

In a learning environment, a common cause of boredom is lack of understanding; for instance, if one is not following or connecting to the material in a class or lecture, it will usually seem boring. However, the opposite can also be true; something that is too easily understood, simple or transparent, can also be boring. Boredom is often inversely related to learning, and in school it may be a sign that a student is not challenged enough, or too challenged. An activity that is predictable to the students is likely to bore them.[31]
The French loanword ennui comes from the very same Late Latin word that gave us annoy — inodiare ("to make loathsome"). We borrowed ennui several centuries after absorbing annoy into the language. Ennui deals more with boredom than irritation - and a somewhat specific sort of boredom at that. It generally refers to the feeling of jadedness that can result from living a life of too much ease. The poet Charles Lloyd described it well in his 1823 Stanzas to Ennui when he referred to that world-weary sensation as a "soul-destroying fiend" which visits with its "pale unrest / The chambers of the human breast / Where too much happiness hath fixed its home."