[1] : The Collaborative International Dictionary of English v.0.48

tandem \tan"dem\, n.
   1. a team of horses harnessed one before the other. "he drove
      tandems." --thackeray.
      1913 webster

   2. a tandem bicycle or other vehicle.
      webster 1913 suppl.

   tandem bicycle or tandem tricycle, one for two persons in
      which one rider sits before the other.
      1913 webster
see also:
tandem bicycle tandem tricycle 

Tricycle >> T Words
Tricycle, definition of term: Tricycle
tricycle_pag1.html

Tandem >> T Words
Tandem, definition of term: Tandem
tandem_pag1.html