The Collaborative International Dictionary of English v.0.48:
Blankly \Blank"ly\, adv. 1. In a blank manner; without expression; vacuously; as, to stare blankly. --G. Eliot. [1913 Webster] 2. Directly; flatly; point blank. --De Quincey. [1913 Webster]WordNet (r) 3.0 (2006):
blankly adv 1: without expression; in a blank manner; "she stared at him blankly"