To complete; to create details from a basic outline, structure or skeleton(verb)
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Use "flesh out" in a sentence
"Even Likari managed to gain a small paunch, though the little boy was far too active to flesh out quickly."
"Back when I wrote Demons Don't Dream, I needed a couple of humorously incidental names to flesh out Dug Mundane's background: his best friend and his girlfriend."
"As I walked around, I tried to flesh out imagined pictures of that earlier reality, with all its maddening and unpossessable detail."