chemotaxis

from WordNet (r) 3.0 (2006)

chemotaxis
    n 1: movement by a cell or organism in reaction to a chemical
         stimulus

from The Collaborative International Dictionary of English v.0.48

Chemotaxis \Chem`o*tax"is\, n. Formerly also Chemiotaxis
\Chem`i*o*tax"is\ [Chemical + Gr. ? arrangement, fr. ? to
   arrange.] (Biol.)
   The sensitiveness exhibited by small free-swimming organisms,
   as bacteria, zoospores of alg[ae], etc., to chemical
   substances held in solution. They may be attracted ({positive
   chemotaxis}) or repelled ({negative chemotaxis}). --
   {Chem`o*tac"tic}, a. -- {Chem`o*tac"tic*al*ly}, adv.
   [Webster 1913 Suppl.] chemotherapeutic