spec. Of a child or animal: not close to being fully grown, (very) young; (also) younger than a particular relative.

That has lived or existed for a relatively short time; that is in the early stage of life or growth… Of a person.

Young, youthful (in age, character, or appearance); characteristic of or belonging to a child or young person.

That is a youngling; young, youthful; (also) †inexperienced (obsolete).

Grown up, full-grown, adult. little waxen, young.

Of a person: young, youthful; not advanced in years. Of a person's age: tender.

Lacking some usual or necessary part; not fully developed, formed, or done; unfinished, incomplete. Also: of less than the full or expected amount…

First in order of time or occurrence; early, young, youthful; primitive.

Not old; not affected by age.

Young, youthful.

New, young, fresh. Obsolete.

Not of age.

Of persons: The period or state of ‘bloom’, vigour, or prosperity. The prime (of life), the bloom (of youth); esp. in phrases, †in youth's flowers, i…

Of persons: Not having a beard.

Not weaned; †immature.

of, resembling, or characteristic of a whelp.

Not yet grown up or fully grown; immature.

adj. Not of full age; youthful, immature.

(un-, prefix1 affix 2 + hatch, v.1)

= infantile, adj. 1.

General attributive. Obsolete.

figurative. Left in an unfinished or immature state.

Of an animal: newly born; not yet licked into shape (see lick, v. 4); frequently (now chiefly) figurative. Hence, of a person: naive, inexperienced…

Young, youthful.

Little.

Juvenile.

figurative. Blooming, in the beauty or flower of youth.

Of a person: somewhat young, fairly young.

figurative. In the bloom of health and beauty, in the prime of youth; flourishing.

Usually derogatory. Of conversation, thought, humour, etc.: befitting children rather than adults; childish, infantile, immature; unsophisticated…

Somewhat young; younger. Frequently opposed to elderly.

dialect. (See quots.)

Small; younger, junior; spec. applied to a ‘peg’ of whisky.

U.S. Of a company: belonging to a group of elite, usually long-established U.S. business organizations, typically banks or law firms.