menacingly

from WordNet (r) 3.0 (2006)

menacingly
    adv 1: in a menacing manner; "the voice at the other end of the
           line dropped menacingly" [syn: {menacingly},
           {threateningly}]

from The Collaborative International Dictionary of English v.0.48

Menacingly \Men"a*cing*ly\, adv.
   In a threatening manner.
   [1913 Webster]

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