In a lengthy way, in a manner that is long and drawn out, especially in time.(adverb)
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Use "lengthily" in a sentence
"I'll write a more lengthily review of the book after I've read it."
"I fell a little like “Bob” in “Lost in Translation” when the director of the Suntory ad that he is doing explains rather lengthily what he wants Bob to emote and the translator says “He says he want you to look at camera with more intensity.”"
"Not every actor can lengthily quote Shakespeare verbatim but those who are successful have a degree of that ephemeral "emotional intelligence" apparent in many other professions."