The Collaborative International Dictionary of English v.0.48:

Attraction \At*trac"tion\, n. [L. attractio: cf. F. attraction.]
   1. (Physics) An invisible power in a body by which it draws
      anything to itself; the power in nature acting mutually
      between bodies or ultimate particles, tending to draw them
      together, or to produce their cohesion or combination, and
      conversely resisting separation.
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   Note: Attraction is exerted at both sensible and insensible
         distances, and is variously denominated according to
         its qualities or phenomena. Under attraction at
         sensible distances, there are, -- (1.)

   Attraction of gravitation, which acts at all distances
      throughout the universe, with a force proportional
      directly to the product of the masses of the bodies and
      inversely to the square of their distances apart. (2.)

   Magnetic, diamagnetic, and electrical attraction, each
      of which is limited in its sensible range and is polar in
      its action, a property dependent on the quality or
      condition of matter, and not on its quantity. Under
      attraction at insensible distances, there are, -- (1.)

   Adhesive attraction, attraction between surfaces of
      sensible extent, or by the medium of an intervening
      substance. (2.)

   Cohesive attraction, attraction between ultimate particles,
      whether like or unlike, and causing simply an aggregation
      or a union of those particles, as in the absorption of
      gases by charcoal, or of oxygen by spongy platinum, or the
      process of solidification or crystallization. The power in
      adhesive attraction is strictly the same as that of
      cohesion. (3.)

   Capillary attraction, attraction causing a liquid to rise,
      in capillary tubes or interstices, above its level
      outside, as in very small glass tubes, or a sponge, or any
      porous substance, when one end is inserted in the liquid.
      It is a special case of cohesive attraction. (4.)

   Chemical attraction, or

   affinity, that peculiar force which causes elementary
      atoms, or groups of atoms, to unite to form molecules.
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   2. The act or property of attracting; the effect of the power
      or operation of attraction. --Newton.
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   3. The power or act of alluring, drawing to, inviting, or
      engaging; an attractive quality; as, the attraction of
      beauty or eloquence.
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   4. That which attracts; an attractive object or feature.
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   Syn: Allurement; enticement; charm.
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The Collaborative International Dictionary of English v.0.48:

Chemical \Chem"ic*al\, a.
   Pertaining to chemistry; characterized or produced by the
   forces and operations of chemistry; employed in the processes
   of chemistry; as, chemical changes; chemical combinations.
   [1913 Webster]

   Chemical attraction or Chemical affinity. See under
      Attraction.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chemical attraction
    n 1: the force attracting atoms to each other and binding them
         together in a molecule; "basic dyes have an affinity for
         wool and silk" [syn: affinity, chemical attraction]