The Collaborative International Dictionary of English v.0.48:

Customary \Cus"tom*a*ry\, n. [OF. coustumier, F. coutumier.]
   A book containing laws and usages, or customs; as, the
   Customary of the Normans. --Cowell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Customary \Cus"tom*a*ry\ (k[u^]s"t[u^]m*[asl]*r[y^]), a. [CF.
   OF. coustumier, F. coutumier. See Custom, and cf.
   Customer.]
   [1913 Webster]
   1. Agreeing with, or established by, custom; established by
      common usage; conventional; habitual.
      [1913 Webster]

            Even now I met him
            With customary compliment.            --Shak.
      [1913 Webster]

            A formal customary attendance upon the offices.
                                                  --South.
      [1913 Webster]

   2. (Law) Holding or held by custom; as, customary tenants;
      customary service or estate.
      [1913 Webster]

WordNet (r) 3.0 (2006):

customary
    adj 1: in accordance with convention or custom; "sealed the deal
           with the customary handshake"
    2: commonly used or practiced; usual; "his accustomed
       thoroughness"; "took his customary morning walk"; "his
       habitual comment"; "with her wonted candor" [syn:
       accustomed, customary, habitual, wonted(a)]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "customary":
   Christian, accepted, accustomed, acknowledged, admitted, approved,
   authentic, authoritative, average, being done, canonical, chronic,
   comme il faut, common, commonplace, conformable, consuetudinary,
   conventional, correct, current, de rigueur, decent, decorous,
   established, evangelical, everyday, faithful, familiar, firm,
   fixed, folk, formal, frequent, general, generally accepted,
   habitual, hallowed, handed down, heroic, hoary, household,
   immemorial, inveterate, legendary, literal, long-established,
   long-standing, meet, mythological, normal, normative, obtaining,
   of long standing, of the faith, of the folk, oral, ordinary,
   orthodox, orthodoxical, popular, predominating, prescribed,
   prescriptive, prevailing, prevalent, proper, received, recognized,
   regular, regulation, right, rooted, routine, scriptural, seemly,
   set, sound, standard, stipulated, stock, textual, time-honored,
   traditional, traditionalistic, tried and true, true, true-blue,
   understood, universal, unwritten, usual, venerable, vernacular,
   widespread, wonted, worshipful