In a manner that is exhausted, worn out, or lacking in vitality; in a way that shows decline from former strength.
From effete (adjective, meaning exhausted or worn out) + -ly. Effete comes from Latin effetus (worn out, exhausted by childbearing), from ex- (out) + fetus (bearing young).
The word effete originally meant 'too tired from childbearing to have more children'—it's a fascinating way Latin used biology to describe exhaustion and decline!
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