NOUN (3)

1. exercise that conditions the body;
- Example: "farm work can be a good conditioner"

2. a trainer of athletes;

3. a substance used in washing (clothing or hair) to make things softer;

The Collaborative International Dictionary of English v.0.48:

conditioner \conditioner\ n.
   1. exercise that conditions the body; as, farmwork can be a
      good conditioner.
      [WordNet 1.5]

   2. a trainer of athletes.
      [WordNet 1.5]

   3. a substance used in washing (clothing or hair) to make
      things softer.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

conditioner
    n 1: exercise that conditions the body; "farm work can be a good
         conditioner"
    2: a trainer of athletes
    3: a substance used in washing (clothing or hair) to make things
       softer