The Collaborative International Dictionary of English v.0.48:

Alternate \Al"ter*nate\ (?; 277), v. t. [imp. & p. p.
   Alternated; p. pr. & vb. n. Alternating.] [L. alternatus,
   p. p. of alternare. See Altern.]
   To perform by turns, or in succession; to cause to succeed by
   turns; to interchange regularly.
   [1913 Webster]

         The most high God, in all things appertaining unto this
         life, for sundry wise ends alternates the disposition
         of good and evil.                        --Grew.
   [1913 Webster]

WordNet (r) 3.0 (2006):

alternating
    adj 1: (of a current) reversing direction; "alternating current"
           [ant: direct]
    2: occurring by turns; first one and then the other;
       "alternating feelings of love and hate" [syn: alternate(a),
       alternating(a)]