juvenile, a. [youthful], [young], [immature].
juvenility, n. youthfulness, immaturity.
K
Keel over. (Colloq.) overturn, [capsize], tip [over].
keen, a. [sharp], acute, trenchant; [penetrating], [shrewd], astute, [discerning]; [piercing], [poignant], excruciating, a crimonious, mordacious, [bitter], [intense], [severe]; eager, [ardent], [ravenous], [vehement].
keep, n. [custody], [charge]; [maintenance], [support]; [stronghold], donjon; [condition], [case].
keep, v. detain, [restrain], [hold], [retain], [repress], [withhold]; [preserve], [conserve]; [maintain], continue; [guard], [shield], [defend], [protect], [screen], [preserve]; [entertain], [harbor]; observe, adhere to, [fulfill]; commemorate, [celebrate], solemnize; [support], sustain, provide for.
keep back. [reserve], [withhold]; [restrain], [repress], [check].
keep company with. associate with, [accompany], go with.
keep down. hold in [subjection], [restrain], [hinder], [subdue].