The Collaborative International Dictionary of English v.0.48:

mist \mist\ (m[i^]st), n. [AS. mist; akin to D. & Sw. mist,
   Icel. mistr, G. mist dung, Goth. ma['i]hstus, AS. m[imac]gan
   to make water, Icel. m[imac]ga, Lith. migla mist, Russ. mgla,
   L. mingere, meiere, to make water, Gr. 'omichei^n to make
   water, 'omi`chlh mist, Skr. mih to make water, n., a mist
   m[=e]gha cloud. [root]102. Cf. Misle, Mizzle, Mixen.]
   1. Visible watery vapor suspended in the atmosphere, at or
      near the surface of the earth; fog.
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   2. Coarse, watery vapor, floating or falling in visible
      particles, approaching the form of rain; as, Scotch mist.
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   3. Hence, anything which dims or darkens, and obscures or
      intercepts vision.
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            His passion cast a mist before his sense. --Dryden.
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   Mist flower (Bot.), a composite plant (Eupatorium
      coelestinum), having heart-shaped leaves, and corymbs of
      lavender-blue flowers. It is found in the Western and
      Southern United States.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Eupatorium coelestinum
    n 1: rhizomatous plant of central and southeastern United States
         and West Indies having large showy heads of clear blue
         flowers; sometimes placed in genus Eupatorium [syn:
         mistflower, mist-flower, ageratum, Conoclinium
         coelestinum, Eupatorium coelestinum]