The Collaborative International Dictionary of English v.0.48:

Painstaking \Pains"tak`ing\ (p[=a]nz"t[=a]k`[i^]ng), a.
   Careful in doing; diligent; faithful; attentive. "Painstaking
   men." --Harris.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Painstaking \Pains"tak`ing\, n.
   The act of taking pains; carefulness and fidelity in
   performance. --Beau. & Fl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

painstaking
    adj 1: characterized by extreme care and great effort;
           "conscientious application to the work at hand";
           "painstaking research"; "scrupulous attention to details"
           [syn: conscientious, painstaking, scrupulous]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "painstaking":
   assiduity, assiduous, assiduousness, conscientious, conscionable,
   diligence, diligent, elaborate, exact, fussy, heedful, industrious,
   industriousness, industry, meticulous, operose, pains,
   painstakingness, punctilious, punctual, scrupulous, sedulous,
   sedulousness, thorough, thoroughgoing, thoroughgoingness,
   thoroughness