Source : Webster's Revised Unabridged Dictionary (1913)

Custom \Cus"tom\ (k[u^]s"t[u^]m), n. [OF. custume, costume,
   Anglo-Norman coustome, F. coutume, fr. (assumed) LL.
   consuetumen custom, habit, fr. L. consuetudo, -dinis, fr.
   consuescere to accustom, verb inchoative fr. consuere to be
   accustomed; con- + suere to be accustomed, prob. originally,
   to make one's own, fr. the root of suus one's own; akin to E.
   so, adv. Cf. {Consuetude}, {Costume}.]
   1. Frequent repetition of the same act; way of acting common
      to many; ordinary manner; habitual practice; usage; method
      of doing or living.

            And teach customs which are not lawful. --Acts xvi.
                                                  21.

            Moved beyond his custom, Gama said.   --Tennyson.

            A custom More honored in the breach than the
            observance.                           --Shak.

   2. Habitual buying of goods; practice of frequenting, as a
      shop, manufactory, etc., for making purchases or giving
      orders; business support.

            Let him have your custom, but not your votes.
                                                  --Addison.

   3. (Law) Long-established practice, considered as unwritten
      law, and resting for authority on long consent; usage. See
      {Usage}, and {Prescription}.

   Note: Usage is a fact. Custom is a law. There can be no
         custom without usage, though there may be usage without
         custom. --Wharton.

   4. Familiar aquaintance; familiarity. [Obs.]

            Age can not wither her, nor custom stale Her
            infinite variety.                     --Shak.

   {Custom of merchants}, a system or code of customs by which
      affairs of commerce are regulated.

   {General customs}, those which extend over a state or
      kingdom.

   {Particular customs}, those which are limited to a city or
      district; as, the customs of London.

   Syn: Practice; fashion. See {Habit}, and {Usage}.