puerile Antonyms

been around full-fledged akamai ageing older age-old fully grown sophisticated smart serious senior fully fledged over the hill in one's prime advanced in years awfully clever as tricky as a monkey as sly as a fox as cunning as a fox as cunning as a cartload of monkeys as clever as a wagonload of monkeys as clever as a cartload of monkeys agile enough ripened ripe antiquated antediluvian ancient ancestral anachronistic agile ageless aging aged advanced antique clever paternal old matured mature grown full-grown full-blown elderly elder earnest adult