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.
      [1913 Webster]

   2. To have relation or reference to something.
      [1913 Webster]

            These words pertain unto us at this time as they
            pertained to them at their time.      --Latimer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pertain
    v 1: be relevant to; "There were lots of questions referring to
         her talk"; "My remark pertained to your earlier comments"
         [syn: refer, pertain, relate, concern, come to,
         bear on, touch, touch on, have-to doe with]
    2: be a part or attribute of [syn: pertain, appertain]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "pertain":
   affect, appertain, appertain to, apply, apply to, associate, bear,
   bear on, befit, combine, concern, connect, cover, include, join,
   pertain to, refer to, regard, relate, relate to, vest