The Collaborative International Dictionary of English v.0.48:

Posture \Pos"ture\ (?; 135), v. t. [imp. & p. p. Postured; p.
   pr. & vb. n. Posturing.]
   To place in a particular position or attitude; to dispose the
   parts of, with reference to a particular purpose; as, to
   posture one's self; to posture a model. --Howell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

posturing
    n 1: adopting a vain conceited posture