/ əˈplɒm; NAmE əˈplɑːm/ noun
[ U ] if sb does sth with aplomb , they do it in a confident and successful way, often in a difficult situation :
with considerable / great / remarkable aplomb
He delivered the speech with his usual aplomb .
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WORD ORIGIN
late 18th cent. (in the sense perpendicularity, steadiness ): from French , from à plomb according to a plumb line.