Source : Webster's Revised Unabridged Dictionary (1913)

Due \Due\, v. t.
   To endue. [Obs.] --Shak.

Due \Due\, a. [OF. deu, F. d[^u], p. p. of devoir to owe, fr. L.
   debere. See {Debt}, {Habit}, and cf. {Duty}.]
   1. Owed, as a debt; that ought to be paid or done to or for
      another; payable; owing and demandable.

   2. Justly claimed as a right or property; proper; suitable;
      becoming; appropriate; fit.

            Her obedience, which is due to me.    --Shak.

            With dirges due, in sad array, Slow through the
            churchway path we saw him borne.      --Gray.

   3. Such as (a thing) ought to be; fulfilling obligation;
      proper; lawful; regular; appointed; sufficient; exact; as,
      due process of law; due service; in due time.

   4. Appointed or required to arrive at a given time; as, the
      steamer was due yesterday.

   5. Owing; ascribable, as to a cause.

            This effect is due to the attraction of the sun.
                                                  --J. D.
                                                  Forbes.

Due \Due\, adv.
   Directly; exactly; as, a due east course.

Due \Due\, n.
   1. That which is owed; debt; that which one contracts to pay,
      or do, to or for another; that which belongs or may be
      claimed as a right; whatever custom, law, or morality
      requires to be done; a fee; a toll.

            He will give the devil his due.       --Shak.

            Yearly little dues of wheat, and wine, and oil.
                                                  --Tennyson.

   2. Right; just title or claim.

            The key of this infernal pit by due . . . I keep.
                                                  --Milton.

Source : WordNet®

due
     adj 1: owed and payable immediately or on demand; "payment is due"
            [syn: {owed}] [ant: {undue}]
     2: proper and appropriate; fitting; "richly deserved
        punishment"; "due esteem" [syn: {deserved}]
     3: scheduled to arrive; "the train is due in 15 minutes" [syn:
        {due(p)}]
     4: suitable to or expected in the circumstances; "all due
        respect"; "due cause to honor them"; "a long due
        promotion"; "in due course" [ant: {undue}]
     5: reasonable in the circumstances; "gave my comments due
        consideration"; "exercising due care"

due
     n 1: that which is deserved or owed; "give the devil his due"
     2: a payment that is due (e.g., as the price of membership);
        "the society dropped him for non-payment of dues"

due
     adv : directly or exactly; straight; "went due North"