The Collaborative International Dictionary of English v.0.48:

Corban \Cor"ban\ (k[^o]r"b[a^]n), n. [Heb. qorb[=a]n, akin to
   Ar. qurb[=a]n.]
   1. (Jewish Antiq.) An offering of any kind, devoted to God
      and therefore not to be appropriated to any other use;
      esp., an offering in fulfillment of a vow.
      [1913 Webster]

   Note: In the old Testament the hebrew word is usually
         translated "oblation" as in --Numb. xviii. 9, xxxi. 50.
         [1913 Webster]

   Note: The traditionists laid down that a man might interdict
         himself by vow, not only from using for himself, but
         from giving to another, or receiving from him, some
         particular object, whether of food or any other kind. A
         person might thus exempt himself from assisting parents
         in distress, under plea of corban. --Dr. W. Smith.
         [1913 Webster]

   2. An alms basket; a vessel to receive gifts of charity; a
      treasury of the church, where offerings are deposited.
      [1913 Webster]

Easton's 1897 Bible Dictionary:

Corban
   a Hebrew word adopted into the Greek of the New Testament and
   left untranslated. It occurs only once (Mark 7:11). It means a
   gift or offering consecrated to God. Anything over which this
   word was once pronounced was irrevocably dedicated to the
   temple. Land, however, so dedicated might be redeemed before the
   year of jubilee (Lev. 27:16-24). Our Lord condemns the Pharisees
   for their false doctrine, inasmuch as by their traditions they
   had destroyed the commandment which requires children to honour
   their father and mother, teaching them to find excuse from
   helping their parents by the device of pronouncing "Corban" over
   their goods, thus reserving them to their own selfish use.