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a. a period of history marked by some feature or characteristic; era
b. (capital when part of a name): the Middle Ages; the Space Age
2. Geology palaeontol
a. a period of the earth's history distinguished by special characteristics
b. the period during which a stage of rock strata is formed; a subdivision of an epoch
3. Myth any of the successive periods in the legendary history of man, which were, according to Hesiod, the golden, silver, bronze, heroic, and iron ages
4. Psychol the level in years that a person has reached in any area of development, such as mental or emotional, compared with the normal level for his chronological age
5. of age adult and legally responsible for one's actions (usually at 18 or, formerly, 21 years)



in humans, a stage of development that is characterized by specific regularities of formation of the organism and personality and by relatively stable morphophysiological and psychological traits. While age is a stage in the biological maturing of the organism, a process controlled by genetic factors, it is also a concrete result and stage of the social-psychological development of the personality and is determined by the conditions of life, training, and upbringing.

The content and form of training and upbringing are historically composed and varied according to age; in their turn they affect the determination of the boundaries and possibilities of a given age. In contemporary pedagogy and developmental psychology, several ages are differentiated with respect to the known relationships of the boundaries: infancy (from birth to one year); pre-preschool, or early childhood (from one to three); preschool (from three to seven); early school age (from seven to ten years); juvenile, or middle school (from ten to 15); and late school, or early youth (15 to 18 years old). Beyond these limits there is no generally accepted classification in the literature; only old age is considered separately. With the increased longevity noted in the 20th century, gerontology and gerontopsychology have arisen as disciplines to study the problems of prolonging the active life of a human being. Each age has a characteristic structure of cognitive, emotional, and volitional properties and qualities; forms of behavior; types of relationships to the environment; and peculiarities of structure and functioning of various organs and systems of the organism. This structure, however, is not invariable: in the 20th century a general acceleration of the physical and mental development of children has been noted. On the other hand, educational theory, in solving the problem of optimizing training, widens the possibilities of age and the boundaries of acquiring knowledge. Training must take into account not only the level of development achieved but also the development perspectives (the concept of “zones of imminent development,” as formulated by L. S. Vygotskii): the teacher must know not only what is present in a child of a given age but also what can be achieved, given certain conditions, by the child in the near future.



Period of time from origin or birth to a later time designated or understood; length of existence.
Any one of the named epochs in the history of the earth marked by specific phases of physical conditions or organic evolution, such as the Age of Mammals.
One of the smaller subdivisions of the epoch as geologic time, corresponding to the stage or the formation, such as the Lockport Age in the Niagara Epoch.


(aerospace engineering)
References in periodicals archive ?
In the first of two related studies, an earlier age of onset for vasomotor symptoms (VMS) was linked with increased endothelial dysfunction as measured by brachial artery ultrasound.
In the girls who exercise regularly the age of onset of menstrual cycle has little delay.
Researchers found that those individuals with a specific genetic signature within a region on chromosome 1 had an age of onset approximately two-and-a-half years earlier (56.
Type 3: Age of onset from 18 months to early adulthood.
Control variables included demographic characteristics (age and employment status) and disability characteristics (visual acuity, visual field restriction, and the age of onset of the disability).
He added: "It stands to reason that women, and probably men, can dramatically delay the age of onset of persistent wrinkles by protecting their skin daily with an effective moisturiser and sunscreen from an early age.
38) While some states use an age other than eighteen (39) and others require onset "during the developmental period" (40) in lieu of designating a specific age of onset, all but one require that the condition manifest before adulthood.
In SASH the CIDI focused on common mental disorders (including depression, anxiety and substance-related disorders) and included the age of onset of disorders.
For example, results from the National Comorbidity Survey Replication study (NCS-R) revealed a median age of onset for anxiety disorders of 11 years, with most participants receiving a diagnosis between the ages of 6 and 22 (Kessler et al.
Primary outcome was age of onset of eczema, and environmental exposures included pet ownership and mite and pet allergen levels.
Dr Ranjan Duara, who led researchers, said: "The combination of heavy drinking and smoking cut the age of onset of Alzheimer's by six to seven years, making them among the most important preventable risk factors.