The Collaborative International Dictionary of English v.0.48:

Pains \Pains\ (p[=a]nz), n.
   Labor; toilsome effort; care or trouble taken; -- plural in
   form, but used with a singular or plural verb, commonly the
   former.
   [1913 Webster]

         And all my pains is sorted to no proof.  --Shak.
   [1913 Webster]

         The pains they had taken was very great. --Clarendon.
   [1913 Webster]

         The labored earth your pains have sowed and tilled.
                                                  --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pains
    n 1: an effortful attempt to attain a goal [syn: striving,
         nisus, pains, strain]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "pains":
   assiduity, assiduousness, diligence, effort, elbow grease,
   endeavor, energy, exertion, hard pull, industriousness, industry,
   long pull, might and main, muscle, nerve and sinew, painstaking,
   painstakingness, sedulousness, thoroughgoingness, thoroughness,
   trouble