characterized by youth; young.

of, pertaining to, or befitting youth

youthful enthusiasm.

having the appearance, freshness, vigor, etc., of youth

She is 60 but her optimism has kept her youthful.

in an early period of existence; early in time.

Physical Geography . (of topographical features) having undergone erosion to a slight extent only.

noun

adolescence , greenness , juvenescence , juvenility , puberty , salad days , spring