Kill"ing*ly

from The Collaborative International Dictionary of English v.0.48

Killing \Kill"ing\, a.
   Literally, that kills; having power to kill; fatal; in a
   colloquial sense, conquering; captivating; irresistible. --
   {Kill"ing*ly}, adv.
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         Those eyes are made so killing.          --Pope.
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         Nothing could be more killingly spoken.  --Milton.
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