The Collaborative International Dictionary of English v.0.48:

Shop \Shop\, v. i. [imp. & p. p. Shopped; p. pr. & vb. n.
   Shopping.]
   To visit shops for the purpose of purchasing goods.
   [1913 Webster]

         He was engaged with his mother and some ladies to go
         shopping.                                --Byron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

shopping
    n 1: searching for or buying goods or services; "went shopping
         for a reliable plumber"; "does her shopping at the mall
         rather than down town"
    2: the commodities purchased from stores; "she loaded her
       shopping into the car"women carrying home shopping didn't
       give me a second glance"

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "shopping":
   buy, buying, buying power, buying up, catalog buying, coemption,
   consumer power, consumer sovereignty, consumerism, cornering,
   emption, hire purchase, impulse buying, installment buying,
   mail-order buying, marketing, money illusion, purchase, purchasing,
   purchasing power, rebuying, repurchase, shopping spree,
   window-shopping