Youngest

superl. of young.
a person who is the least old of a group, as the youngest member of a family:
their youngest is still in high school.
being in the first or early stage of life or growth; youthful; not old:
a young woman.
having the appearance, freshness, vigor, or other qualities of youth.
of or relating to youth:
in one’s young days.
inexperienced or immature.
not far advanced in years in comparison with another or others.
junior, as applied to the younger of two persons having the same name:
the young mr. smith.
being in an early stage generally, as of existence, progress, operation, development, or maturity; new; early:
a young wine; it is a young company, not yet firmly established.
representing or advocating recent or progressive tendencies, policies, or the like.
those who have youth; young persons collectively:
the educated young of today; a game for young and old.
young offspring:
a mother hen protecting her young.
with young, (of an animal) pregnant.
contemporary examples

hatchet job of the year 2014 shortlist announced the telegraph january 18, 2014
what made the beatles so big? diagnosing ‘beatlemania’ john mcmillian october 30, 2013
krim case sparks a nanny backlash paula froelich october 27, 2012
mark wahlberg’s pardon plea: a look back at his troubling, violent, and racist rap sheet marlow stern december 6, 2014
bibi and young american jews peter beinart november 12, 2012

historical examples

the science of fairy tales edwin sidney hartland
weighed and wanting george macdonald
my miscellanies, vol. 2 (of 2) wilkie collins
dust mr. and mrs. haldeman-julius
concord days a. bronson alcott

adjective younger (ˈjʌŋɡə), youngest (ˈjʌŋɡɪst)

having lived, existed, or been made or known for a relatively short time: a young man, a young movement, a young country
(as collective noun; preceded by the): the young

youthful or having qualities -ssociated with youth; vigorous or lively: she’s very young for her age
of or relating to youth: in my young days
having been established or introduced for a relatively short time: a young member
in an early stage of progress or development; not far advanced: the day was young
(geography)

(of mountains) formed in the alpine orogeny and still usually rugged in outline
another term for youthful (sense 4)

(often capital) of or relating to a rejuvenated group or movement or one claiming to represent the younger members of the population, esp one adhering to a political ideology: young england, young socialists
noun
(functioning as pl) offspring, esp young animals: a rabbit with her young
with young, (of animals) pregnant
noun
brigham (ˈbrɪɡəm). 1801–77, us mormon leader, who led the mormon migration to utah and founded salt lake city (1847)
edward. 1683–1765, english poet and dramatist, noted for his night thoughts on life, death, and immortality (1742–45)
lester. 1909–59, us saxophonist and clarinetist. he was a leading early exponent of the tenor saxophone in jazz
neil (percival). born 1945, canadian rock guitarist, singer, and songwriter. his alb-ms include harvest (1972), rust never sleeps (1979), ragged glory (1990), and prairie wind (2005)
thomas. 1773–1829, english physicist, physician, and egyptologist. he helped to establish the wave theory of light by his experiments on optical interference and -ssisted in the decipherment of the rosetta stone
adj.
n.
young
(yŭng)
british physicist and physician who is best known for his contributions to the wave theory of light and his discovery of how the lens of the human eye changes shape to focus on objects of different distances. he also studied surface tension and elasticity, and young’s modulus (a measure of the rigidity of materials) is named for him. he is also credited with the first scientific definition of the word energy.