Blethen (adj.) the blank, sheepish facial expression that young, innocent or inexperienced persons assume when confronted with the hairier aspects of what others consider to be "real life" (i.e. on the countryside; in "da hood"; in prison; among lower social classes as one comes from; explicit and / or embarrassing biological phenomena, etcetera)
Mathilda stood dumbstruck, her Victorian floral dress fluttering in the chilly highland wind.
"Don't stand there like a blethen public school-lass!", Prue laughed as she tried to pull the calf out "It's probably got just one 'ead!"
-- "Wavering Heights", Ethel Porridge
Tralalilly
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... then softly she began to sing / a theme of sleep and slumbering wandering, woven with deeper spell / than songs wherewith in ancient dell Melian did once the twilight fill / profound, and fathomless, and still.
-- the Lay of Leithian, J.R.R. Tolkien