The Collaborative International Dictionary of English v.0.48:

Abruptly \Ab*rupt"ly\, adv.
   1. In an abrupt manner; without giving notice, or without the
      usual forms; suddenly.
      [1913 Webster]

   2. Precipitously.
      [1913 Webster] Abruptly pinnate

WordNet (r) 3.0 (2006):

abruptly
    adv 1: quickly and without warning; "he stopped suddenly" [syn:
           abruptly, suddenly, short, dead]