The Collaborative International Dictionary of English v.0.48:

Mien \Mien\ (m[=e]n), n. [F. mine; perh. from sane source as
   mener to lead; cf. E. demean, menace, mine, n.]
   Aspect; air; manner; demeanor; carriage; bearing.
   [1913 Webster]

         Vice is a monster of so frightful mien,
         As, to be hated, needs but to be seen.   --Pope.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mien
    n 1: dignified manner or conduct [syn: bearing, comportment,
         presence, mien]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "mien":
   action, actions, activity, acts, address, affectation, air,
   appearance, aspect, bearing, behavior, behavior pattern,
   behavioral norm, behavioral science, brow, carriage, cast,
   cast of countenance, color, complexion, comportment, conduct,
   countenance, culture pattern, custom, demeanor, deportment, doing,
   doings, expression, exteriority, externality, externalness,
   extrinsicality, face, facial appearance, favor, feature, features,
   folkway, foreignness, garb, gestures, goings-on, guise, lineaments,
   lines, look, looks, maintien, manner, mannerism, manners, method,
   methodology, methods, modus vivendi, motions, movements, moves,
   observable behavior, openness, outerness, outward appearance,
   outwardness, pattern, physiognomy, poise, port, pose, posture,
   practice, praxis, presence, procedure, proceeding, seeming, set,
   shallowness, social science, stance, style, superficiality,
   tactics, tone, traits, turn, visage, way, way of life, ways