The Collaborative International Dictionary of English v.0.48:

Modality \Mo*dal"i*ty\, n. [Cf. F. modalit['e].]
   1. The quality or state of being modal.
      [1913 Webster]

   2. (Logic & Metaph.) A modal relation or quality; a mode or
      point of view under which an object presents itself to the
      mind. According to Kant, the quality of propositions, as
      assertory, problematical, or apodeictic.
      [1913 Webster]

WordNet (r) 3.0 (2006):

modality
    n 1: a classification of propositions on the basis of whether
         they claim necessity or possibility or impossibility [syn:
         modality, mode]
    2: verb inflections that express how the action or state is
       conceived by the speaker [syn: mood, mode, modality]
    3: a particular sense [syn: modality, sense modality,
       sensory system]
    4: a method of therapy that involves physical or electrical
       therapeutic treatment

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "modality":
   Platonic form, Platonic idea, aesthetic form, archetype, art form,
   bearings, build, case, cast, circumstance, condition,
   configuration, conformation, cut, estate, fashion, figuration,
   figure, fix, footing, form, format, formation, frame, genre,
   impression, inner form, jam, layout, location, lot, make, makeup,
   matrix, mode, model, mold, pass, pattern, pickle, place, plight,
   position, posture, predicament, prototype, rank, set, shape,
   significant form, situation, spot, stamp, standing, state, station,
   status, structure, style, turn, type