He is constantly striving to keep in touch with the unlessoned innocence of his youth.
unlessoned in American English
(unˈlesənd)
adjective
not educated or trained
Word origin
[1540–50; un-1 + lesson + -ed3]This word is first recorded in the period 1540–50. Other words that entered Englishat around the same time include: gondola, labyrinth, monitor, platform, vacuumun- is a prefix meaning “not,” freely used as an English formative, giving negative oropposite force in adjectives and their derivative adverbs and nouns (unfair; unfairly; unfairness; unfelt; unseen; unfitting; unformed; unheard-of; un-get-at-able), and less freely used in certain other nouns (unrest; unemployment); -ed is a suffix forming adjectives from nouns. Other words that use the affix -ed include: bearded, monied, tender-hearted