幻を追う[maboroshiwoou] to pursue an illusion
幻影[genei] phantom
幻覚[genkaku] hallucination
幻覚剤[genkakuzai] hallucinogen
幻姿[genshi] apparition

幻視[genshi] visual hallucination
幻想[gensou] illusions
幻想劇[gensougeki] non-realistic drama
幻像[genzou] phantom

乳幼児[nyuuyouji] infants
幼い[osanai] very young
幼馴染[osananajimi] childhood friend
幼魚[yougyo] fry (young fish)
幼形進化[youkeishinka] paedomorphosis

幼子[osanago] infant
幼児[youji] infant
幼児ポルノ[youjiporuno] child pornography
幼児語[youjigo] baby talk (like choo-choo for train, etc.)
幼時[youji] childhood