Noun

A noun (from Latin nōmen, literally meaning "name") is a word that functions as the name of some specific thing or set of things, such as living creatures, objects, places, actions, qualities, states of existence, or ideas.Linguistically, a noun is a member of a large, open part of speech whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition.

Lexical categories (parts of speech) are defined in terms of the ways in which their members combine with other kinds of expressions. The syntactic rules for nouns differ from language to language. In English, nouns are those words which can occur with articles and attributive adjectives and can function as the head of a noun phrase.

History

Word classes (parts of speech) were described by Sanskrit grammarians from at least the 5th century BC. In Yāska's Nirukta, the noun (nāma) is one of the four main categories of words defined.

The Ancient Greek equivalent was ónoma (ὄνομα), referred to by Plato in the Cratylus dialog, and later listed as one of the eight parts of speech in The Art of Grammar, attributed to Dionysius Thrax (2nd century BC). The term used in Latin grammar was nōmen. All of these terms for "noun" were also words meaning "name". The English word noun is derived from the Latin term, through the Anglo-Norman noun.

Mood disorder

Mood disorder is a group of diagnoses in the Diagnostic and Statistical Manual of Mental Disorders classification system where a disturbance in the person's mood is hypothesized to be the main underlying feature. The classification is known as mood (affective) disorders in International Classification of Diseases (ICD).

English psychiatrist Henry Maudsley proposed an overarching category of affective disorder. The term was then replaced by mood disorder, as the latter term refers to the underlying or longitudinal emotional state, whereas the former refers to the external expression observed by others.

Mood disorders fall into the basic groups of elevated mood such as mania or hypomania, depressed mood of which the best-known and most researched is major depressive disorder (MDD) (commonly called clinical depression, unipolar depression, or major depression), and moods which cycle between mania and depression known as bipolar disorder (BD) (formerly known as manic depression). There are several sub-types of depressive disorders or psychiatric syndromes featuring less severe symptoms such as dysthymic disorder (similar to but milder than MDD) and cyclothymic disorder (similar to but milder than BD). Mood disorders may also be substance-induced or occur in response to a medical condition.

Seasonal affective disorder

Seasonal affective disorder (SAD), also known as winter depression, winter blues, summer depression, summertime sadness, or seasonal depression, is a mood disorder subset in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or summer.

In the Diagnostic and Statistical Manual of Mental Disorders DSM-IV and DSM-5, its status was changed. It is no longer classified as a unique mood disorder but is now a specifier called with seasonal pattern for recurrent major depressive disorder that occurs at a specific time of the year and fully remits otherwise. Although experts were initially skeptical, this condition is now recognized as a common disorder. SAD's prevalence in the U.S. ranges from 1.4% in Florida to 9.9% in Alaska.

The U.S. National Library of Medicine notes that "some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and may also feel depressed. Though symptoms can be severe, they usually clear up." The condition in the summer can include heightened anxiety.