The Collaborative International Dictionary of English v.0.48:
Stiffly \Stiff"ly\, adv. In a stiff manner. [1913 Webster]WordNet (r) 3.0 (2006):
stiffly adv 1: in a stiff manner; "his hands lay stiffly" [syn: stiffly, stiff] 2: in a rigid manner; "the body was rigidly erect"; "he sat bolt upright" [syn: rigidly, stiffly, bolt]