1.  The quality or state of being young; youthfulness; juvenility. Milton. [1913 Webster]
"Such as in his face
Youth smiled celestial." [1913 Webster]

2.  The part of life that succeeds to childhood; the period of existence preceding maturity or age; the whole early part of life, from childhood, or, sometimes, from infancy, to manhood. [1913 Webster]
"He wondered that your lordship
Would suffer him to spend his youth at home." [1913 Webster]
"Those who pass their youth in vice are justly condemned to spend their age in folly." [1913 Webster]

3.  A young person; especially, a young man. [1913 Webster]
"Seven youths from Athens yearly sent." [1913 Webster]

4.  Young persons, collectively. [1913 Webster]
"It is fit to read the best authors to youth first." [1913 Webster]

youth, n. (pl. youths)
1 the state of being young; the period between childhood and adult age.
2 the vigour or enthusiasm, inexperience, or other characteristic of this period.
3 an early stage of development etc.
4 a young person (esp. male).
5 (pl.) young people collectively (the youth of the country).

Idiom:
youth club (or centre) a place or organization provided for young people's leisure activities. youth hostel a place where (esp. young) holiday-makers can put up cheaply for the night. youth hosteller a user of a youth hostel.

Etymology:
OE geoguth f. Gmc, rel. to YOUNG

N  newness, novelty, recency, immaturity, youth, gloss of novelty, innovation, renovation, modernism, mushroom, parvenu, latest fashion, new, novel, recent, fresh, green, young, evergreen, raw, immature, unsettled, yeasty, virgin, untried, unhandseled, untrodden, untrod, unbeaten, fire-new, span-new, late, modern, neoteric, hypermodern, nouveau, new-born, nascent, neonatal, new-fashioned, new-fangled, new-fledged, of yesterday, just out, brand-new, up to date, up to the minute, with it, fashionable, in fashion, in, hip, vernal, renovated, sempervirent, sempervirid, fresh as a rose, fresh as a daisy, fresh as paint, spick and span, newly, afresh, anew, lately, just now, only yesterday, the other day, latterly, of late, not long ago, a short time ago, di novello tutto par bello, nullum est jam dictum quod non dictum est prius, una scopa nuova spazza bene.

N  youth, juvenility, juvenescence, juniority, infancy, babyhood, childhood, boyhood, girlhood, youthhood, incunabula, minority, nonage, teens, tender age, bloom, cradle, nursery, leading strings, pupilage, puberty, pucelage, prime of life, flower of life, springtide of life, seedtime of life, golden season of life, heyday of youth, school days, rising generation, young, youthful, juvenile, green, callow, budding, sappy, puisne, beardless, under age, in one's teens, in statu pupillari, younger, junior, hebetic, unfledged, youth on the prow and pleasure at the helm, youth a the glad season of life.

N  infant, babe, baby, babe in arms, nurseling, suckling, yearling, weanling, papoose, bambino, kid, vagitus, child, bairn, little one, brat, chit, pickaninny, urchin, bantling, bratling, elf, youth, boy, lad, stripling, youngster, youngun, younker, callant, whipster, whippersnapper, whiffet, schoolboy, hobbledehoy, hopeful, cadet, minor, master, scion, sap, seedling, tendril, olive branch, nestling, chicken, larva, chrysalis, tadpole, whelp, cub, pullet, fry, callow, codlin, codling, foetus, calf, colt, pup, foal, kitten, lamb, lambkin, aurelia, caterpillar, cocoon, nymph, nympha, orphan, pupa, staddle, girl, lass, lassie, wench, miss, damsel, demoiselle, maid, maiden, virgin, hoyden, infantine, infantile, puerile, boyish, girlish, childish, babyish, kittenish, baby, newborn, unfledged, new-fledged, callow, in the cradle, in swaddling clothes, in long clothes, in arms, in leading strings, at the breast, in one's teens.

N  weakness, debility, atony, relaxation, languor, enervation, impotence, infirmity, effeminacy, feminality, fragility, flaccidity, inactivity, anaemia, bloodlessness, deficiency of blood, poverty of blood, declension of strength, loss of strength, failure of strength, delicacy, invalidation, decrepitude, asthenia, adynamy, cachexy, cachexia, sprain, strain, reed, thread, rope of sand, house of cards, softling, weakling, infant, youth, weak, feeble, debile, impotent, relaxed, unnerved sapless, strengthless, powerless, weakly, unstrung, flaccid, adynamic, asthenic, nervous, soft, effeminate, feminate, womanly, frail, fragile, shattery, flimsy, unsubstantial, insubstantial, gimcrack, gingerbread, rickety, creaky, creaking, cranky, craichy, drooping, tottering, broken, lame, withered, shattered, shaken, crazy, shaky, palsied, decrepit, languid, poor, infirm, faint, faintish, sickly, dull, slack, evanid, spent, short-winded, effete, weather-beaten, decayed, rotten, worn, seedy, languishing, wasted, washy, laid low, pulled down, the worse for wear, unstrengthened, unsupported, unaided, unassisted, aidless, defenseless, cantilevered (support), on its last legs, weak as a child, weak as a baby, weak as a chicken, weak as a cat, weak as a rat, weak as water, weak as water gruel, weak as gingerbread, weak as milk and water, colorless, non sum qualis eram.

bloom of youth, fountain of youth, lautaro youth movement, youth crusade, youth culture, youth gang, youth hostel, youth movement, youth subculture