The Collaborative International Dictionary of English v.0.48:

Pertain \Per*tain"\, v. i. [imp. & p. p. Pertained; p. pr. &
   vb. n. Pertaining.] [OE. partenen, OF. partenir, fr. L.
   pertinere to stretch out, reach, pertain; per + tenere to
   hold, keep. See Per-, and Tenable, and cf. Appertain,
   Pertinent.]
   1. To belong; to have connection with, or dependence on,
      something, as an appurtenance, attribute, etc.; to
      appertain; as, saltness pertains to the ocean; flowers
      pertain to plant life.
      [1913 Webster]

            Men hate those who affect that honor by ambition
            which pertaineth not to them.         --Hayward.
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   2. To have relation or reference to something.
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            These words pertain unto us at this time as they
            pertained to them at their time.      --Latimer.
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Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "pertaining":
   a propos, ad rem, admissible, affinitive, appertaining, applicable,
   applying, apposite, appropriate, apropos, associative, belonging,
   comparable, comparative, congenial, connective, correlative,
   en rapport, germane, in point, involving, linking, material,
   pertinent, proportionable, proportional, proportionate, referable,
   referring, relating, relational, relative, relevant, sympathetic,
   to the point, to the purpose