0 years : birth.
0 years, minus 6/12 years : embryonic development.
0 years, minus 7/12 years : embryogenesis, the development of a human being from the time of implantation to the end of the eighth week after conception.
0 years, minus 8/12 to 9/12 years : ovulation, fertilization, morula-blastocyst formation and implantation.
0 years, minus 9/12 years : gametogenesis, the production of gametes; the first period of prenatal change; the initial stage of progressive individuation.
0-6 years : infancy; the ages of children kept in a nursery, child-care facility, pre-school tutorship, or kindergarden. Cf. infancy.
0-13 years : tutela, the guardianship of a prepubescent child. Cf. 14-25 years, cura.
0-13 years : prepubescence; infancy and early childhood; the first period of postnatal change; the fifth period of progressive individuation.
0-20 years : civil infancy; the first part of life. English common law eventually established 21 years as the beginning of civil adulthood, and called any age younger than that ‘infancy’ for legal purposes. Noah Webster similarly contrasted adulthood with a long term of infancy in 1806. Cf. infancy.
6-7 years : maritagium incohatus, inchoate marriage; inceptive marriage, the beginning or commencement of marriage; the lower age limit for arranged marriages. Medieval societies sometimes encouraged puerile marriages, or inchoate marriages, but normally respected the spouse’s right of consent when the spouse reached maturity at 12-14 years.
7-08 years in males : early childhood.
7-13 years : 1 x 7 years; puer, puella; the ages at which a child’s incapacity for crime becomes uncertain, and the presumption of a child’s innocence becomes a rebuttable proposition. A puer is a boy between infancy and puberty, or under 14 years, whereas a puella attains puberty earlier, at 12 years.
08-10 years in females : middle childhood.
09-11 years in males : middle childhood.
12-13 years in males : prepuberty; late childhood.
07 years in females : early childhood.
08 years : age limit for the removal of the right lacteal gland of an Amazon girl. Greek historians tell us that Amazons removed their right breasts by burning a girl’s chest with hot irons, long before to puberty, to provide her the maneuverability she would need to handle a bow. Although several Amazon burial sites have been found, we have little corroborating evidence of this legend. This obscure statute has long been remarkable for its novelty, and it provokes a critical question: What fate befell girls who were born left-handed? Cf. 16 years.
10 years :  age of consent to a sexual proposition.
11 years in females : prepuberty; late childhood.
12 years : pubertas muliebris, muliebrity, female puberty, female adolescence; the age at which a woman reaches puberty; the age at which a child could be promised or wedded to another, subject to their mutual consent by 14 years of age.
13 years : age of consent to a sexual proposition. The English raised this age to 16 years in the Criminal Law Amendment Act of 1885.
14 years :  age of sex play, regardless of consent. The British outlawed all sex play with children younger than 14 years of age, regardless of consent, in the Indecency with Children Act (1960).
14 years : 2 x 7 years; pubertas virilis, ætas pubertatis, virility; male puberty, male adolescence; the age of discretion, when a child betrothed in childhood acquired the right of consent to his or her marriage; the age at which a man reaches puberty.
14 years : the age of a boy crowned and sacrified by the Pentitentes on Easter.
14-17 years : ages apropros for a hearing or trial in junenile court, when the age of majority is fixed at 18 years.
14-17 years in males : adolescence.
14-20 years : ages that qualified for judgment by a juvenile court, when majority is deemed to be 21 years.
14-25 years : cura, the guardianship of a child in puberty, adolescence, and young adulthood. Cf. 0-13 years, tutela.
14-27 years : adolescence, youth, the time succeeding childhood and puberty.
15 years : feudal majority for a female, when a female heir to the tenancy of a fee could assume that tenancy in her own right. Cf. 20 years for a male.
15-16 years : ætas virilis, adult; the fifteenth or sixteenth year, when a Roman male assumed the toga virilis.
15-30 years : ætas adulescens, adolescence, elsewhere conservatively defined at 14-27 years of age.
16 years : ætas rædarilis [NL] driving age; the age at which a youngster may obtain a driver’s license, in many states.
16 years : age of consent to a sexual proposition. The English raised this age from 13 years to 16 years in the Criminal Law Amendment Act of 1885.
16 years : the age when a male of the Chukchi or Inuit might dress as a woman, anticipating his succession as a tribal shaman (choupan). Cf. 8 years.
17-46 years : ætas militaris : military age, seventeenth year, the year one becomes eligible for military service. The legal period of military service in Rome was from 17 to 46 years.
18 years : ætas diplomatis, high school graduation; ætas potoralis, drinking age in many states; voting age for U.S. federal elections. This age has replaced 21 years as the age of maturity or majority in many jurisdictions, especially in the United States.
18-20 years : early adulthood, the initial stages of regressive individuation; the inhalation of adulthood.
18-35 years : Fareita, the first of four Konso age-grades; men who provide communal labor.
19 years : ætas parentis, age of parentage. Thomas Jefferson customarily used 19 years as a standard generational period for his genealogical estimates, and he claimed to have arrived at that number by examining a large sampling of records.
19 years : yakudoshi, female specific; an unlucky year for a Japanese female. Cf. 33 years.
20 years : feudal majority for a male, when an heir male to the tenancy of a fee could assume that tenancy in his own right; viginti annos natus, twenty years of age. Cf. 15 years for a female.
20 years : legal majority for both sexes, when the person acquires the power to administer and alienate personal property. Cf. feudal majority (15 & 20 years respectively for women and men), perfect majority (26 years).
20-45 years : ætas iuventas : youthful manhood, elsewhere conservatively defined as 28 to 48 years of age.
21 years : 3 x 7 years; adulthood, majority; imperfect majority; civil adulthood, the statute age of full maturity in many jurisdictions. Our modern and familiar majority of 21 years probably derived from feudal majority at 20 years, the extra year having been added as a measure of surety. English law eventually defined adulthood as any age 21 years and older, and classified any younger age as infancy, for civil purposes. During the twentieth century, many American jurisdictions redefined majority at the lower age of 18 years.
21 years : prima materia; the center-point of adulthood in regressive individuation.
21-27 years : late adulthood, the final stages of regressive individuation; the exhalation of adulthood.
25 years : ætas adulta : adulthood, maturity. Cf. iuventas.
25 years : ætas quæstoria : twenty-fifth year, the age at which one might be appointed questor.
25 years : ætas senatoria : twenty-fifth year, the age at which one might be appointed senator.
25 years : yakudoshi, an unlucky year for a Japanese male. Cf. 42 years.
26 years : perfect majority, the age at which a person acquires the capacity to manage or dispose of all kinds of property, both personal and real. Cf. legal majority (20 years) and feudal majority (15 & 20 years respectively for women and men).
28 years : first conjunction of life, ruled by earth; the conjunction of adulthood and middle age; a milestone in regressive individuation.
28 years : 4 x 7 years; perfect majority, that age that commences middle age. When a U.S. federal statute regulating tobacco sales became effective in February 1997, it required merchants to check the identity papers of anyone seeming to be 28 years or younger, aiming to more effectively enforce the rule that youngsters cannot purchase tobacco until the age of 21 years. The requirement seemed to mirror the old concept of a perfect majority at 28 years.
28-34 years : the inhalation of middle age; a stage of regressive individuation.
30 years : the minimum age for visitational, heterosexual marriage, in Sparta. Cf. 35 years.
30 years : thirtieth birthday. Ethnic diversity and commercialism in America probably account for the common practice of celebrating maturation according to decades, rather than by peculiar Roman and medieval conventions.
33 years : yakudoshi, female specific; an especially perilous age for a Japanese woman. Cf. 19 years.
35 years : black putrefaction; the center-point of middle age in regressive individuation.
35 years : the age beyond which homosexual relations were prohibited in Sparta. Cf. 30 years.
35 years : 7 lustra; 7 x 5 years; the minimum age for the U.S. President. A candidate for president must also have been a resident of the United States for 14 years before he may qualify. Thus, an candidate of minimum age would need to have resided in the United States since the age of 21 years.
35-41 years : the exhalation of middle age; a maturational stage of regressive individuation.
36-53 years : Chela, the second of four Konso age-grades; men who raise families.
39 years : Jack Benny’s age, a jocular expression for an unrevealed age. A person forty years and older, but reluctant to state his or her age, is likely to say ‘thirty-nine.’
40 years : fortieth birthday, the modern milestone for middle age. Forty marks the commencement of a decade in which a woman will experience menopause, and a man will sometimes experience an analogous change of life. In his fifth decade, a man is likely to abandon or change his career, or found his own business.
42 years : 6 x 7 years; second conjunction of regressive individuation, ruled by the moon; the conjunction of middle age and late middle age; a milestone in regressive individuation.
42 years : yakudoshi, male specific; an especially unlucky year for a Japanese male. Cf. 25 years, 60 years.
42-48 years : the inhalation of middle age; a stage of regressive individuation.
43 years : ætas consularis : forty-third year, the age at which one might lawfully be chosen consul. The consul was one of the two highest magistrates at Rome, who was elected annually.
45 years : the age of recklessness for many men; the approximate age of a man’s change of life, or so-called ‘male menopause.’
45-50 years : the proximate ages of menopause in a woman, or a change of life in a man. Even if ovulation continues, natural childbirth is nonetheless rare at these advanced ages. The uterus remains unaffected by menopause, for a woman can incubate and carry to term an egg fertilized in vitro, and the record for surrogate motherhood stands at 63 years of age.
46 years : when old age begins, according to common opinion; the approximate age of menopause.
46-100 years : old age and decrepitude, a period embracing both ætas senecta and ætas vetulus.
49 years : old age.
49 years : 7 x 7 years; yellow putrefaction; the center-point of late middle age in regressive individuation.
49-55 years : the exhalation of middle age; a stage of regressive individuation.
50 years : quinquagenarian; old age, over fifty; fiftieth birthday.
54-71 years : Gada, the third of four Konso age-grades; men who occupy the highest offices.
55 years : early retirement. Employers today tend to offer reduced benefits to employees for opting to retire ten years earlier than age sixty-five.
56 years : 8 x 7 years; third conjunction of regressive individuation, ruled by the sun; the conjunction of late middle age and old age; a milestone in regressive individuation.
56-62 years : the inhalation of old age; a stage of regressive individuation.
60 years : sexagenarius, sexagenary; sexagenarian, one 60 years of age and older.
60 years : yakudoshi, an unlucky year for a Japanese male. Cf. 25 years, 42 years.
63 years : 9 x 7 years; red putrefaction; the center-point of old age in regressive individuation.
63 years : the record for surrogate childbirth, established in 1996.
63-69 years : the exhalation of old age; a stage of regressive individuation.
65 years : retirement age, the age at which a person relinquishes office. Otto von Bismark arbitrarily fixed retirement age at sixty-five years in the 1870s. The U.S. Congress has lately established a schedule for increasing the age of retirement, for the purpose of preserving Social Security benefits.
70 years : ætatis suæ 70 annos, at 70 years of age.
70 years : 10 x 7 years; fourth conjunction of regressive individuation, ruled by heaven; the conjunction of old age and death; a milestone in regressive individuation.
70 years : septuagenarian, one 70 years of age and older.
72-89 years : Orshada, the fourth of four Konso age-grades; wisemen who consult the younger men.
73 years : the age of Charlie Chaplin when he fathered a child.
77 years : 11 x 7 years.
80 years : octogenarian, one 80 years of age and older.
84 years : 12 x 7 years.
90 years : nonagenarian, one 90 years of age and above.
100 years : centenarian, someone 100 years of age or more, thriving beyond the theoretical limit of a human lifetime.
100 years : sæculum : century mark, the theoretical upper limit of a human life.
110 years : the ideal age, which matched the canonical number 110. The Hebrew Patriarch Joseph died at 110 years, and Egyptians regarded 110 to be a sacred number. The Etruscans held 110 to represent 5 x 22 years, and used it for calendar reckoning. The lustra was a cycle of 5 years, and 22 lustra equaled 110 years. Thus, the Romans regularly adjusted the lunar year to the solar year by intercalating extra days at the end of each cycle, and the extra days provided a long holiday for the Saecular Games.
122 years :  the modern record for longevity. Jeanne-Luc Calment of Arles, France, was born on 21 February 1875, and died on 4 August 1997 at 122 years of age. She married her cousin Fernand Nicolas Calment in 1896, but he died in 1942, so her widowhood lasted 55 years. She outlived her daughter, and even her grandson.