The Collaborative International Dictionary of English v.0.48:

Pertinent \Per"ti*nent\, a. [L. pertinens, -entis, p. pr. of
   pertinere: cf. F. pertinent. See Pertain.]
   1. Belonging or related to the subject or matter in hand; fit
      or appropriate in any way; adapted to the end proposed;
      apposite; material; relevant; as, pertinent illustrations
      or arguments; pertinent evidence.
      [1913 Webster]

   2. Regarding; concerning; belonging; pertaining. [R.]
      "Pertinent unto faith." --Hooker.
      [1913 Webster]

   Syn: Apposite; relevant; suitable; appropriate; fit.
        [1913 Webster] -- Per"ti*nent*ly, adv. --
        Per"ti*nent*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

pertinent
    adj 1: having precise or logical relevance to the matter at
           hand; "a list of articles pertinent to the discussion";
           "remarks that were to the point"
    2: being of striking appropriateness and pertinence; "the
       successful copywriter is a master of apposite and evocative
       verbal images"; "an apt reply" [syn: apposite, apt,
       pertinent]

Moby Thesaurus II by Grady Ward, 1.0:

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



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PERTINENT, evidence. Those facts which tend to prove the allegations of the
party offering them, are called pertinent; those which have no such tendency
are called impertinent, 8 Toull. n. 22. By pertinent is also meant that
which belongs. Willes, 319.