The Collaborative International Dictionary of English v.0.48:

Lotion \Lo"tion\, n. [L. lotio, fr. lavare, lotum, to wash: cf.
   F. lotion. See Lave to wash.]
   1. A washing, especially of the skin for the purpose of
      rendering it fair.
      [1913 Webster]

   2. A liquid preparation for bathing the skin, or an injured
      or diseased part, either for a medicinal purpose, or for
      improving its appearance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lotion
    n 1: any of various cosmetic preparations that are applied to
         the skin
    2: liquid preparation having a soothing or antiseptic or
       medicinal action when applied to the skin; "a lotion for dry
       skin" [syn: lotion, application]