Synonym: callow, childish, fresh, juvenile, young. Antonym: aged, grown-up. Similar words: truthful, truthfulness, slothful, faithful, faithfully, unfaithful, wishful, bashful. Meaning: [juːθfʊl] 
adj. suggestive of youth; vigorous and fresh.
adj. suggestive of youth; vigorous and fresh. 241, I was completely stage-struck and my youthful passion was going to see Shakespeare in Stratford.
242, Though still youthful and strikingly petite, his tussled hair has greyed and his lips purse tightly as if against a lifetime of indignities.
More similar words: truthful, truthfulness, slothful, faithful, faithfully, unfaithful, wishful, bashful, watchful, reproachful, watchfulness, youth, south, mouth, truth, southern, uncouth, sleuth, author, untruth, in truth, southeast, mouthing, ruthless, authentic, south pole, southwest, hand to mouth, mouthpiece, authorize.