1. [n]  a variable in a logical or mathematical expression whose value determines the dependent variable; if f(x)=y, x is the independent variable
2. [n]  a summary of the subject or plot of a literary work or play or movie; "the editor added the argument to the poem"
3. [n]  a fact or assertion offered as evidence that something is true; "it was a strong argument that his hypothesis was true"
4. [n]  a discussion in which reasons are advanced for and against some proposition or proposal; "the argument over foreign aid goes on and on"
5. [n]  a contentious speech act; a dispute where there is strong disagreement; "they were involved in a violent argument"

1. \Ar"gu*ment\, n. [F. argument, L. argumentum, fr.
   arguere to argue.]
   1. Proof; evidence. [Obs.]
            There is.. no more palpable and convincing argument
            of the existence of a Deity.          --Ray.
            Why, then, is it made a badge of wit and an argument
            of parts for a man to commence atheist, and to cast
            off all belief of providence, all awe and reverence
            for religion?                         --South.
   2. A reason or reasons offered in proof, to induce belief, or
      convince the mind; reasoning expressed in words; as, an
      argument about, concerning, or regarding a proposition,
      for or in favor of it, or against it.
   3. A process of reasoning, or a controversy made up of
      rational proofs; argumentation; discussion; disputation.
            The argument is about things, but names. --Locke.
   4. The subject matter of a discourse, writing, or artistic
      representation; theme or topic; also, an abstract or
      summary, as of the contents of a book, chapter, poem.
            You and love are still my argument.   --Shak.
            The abstract or argument of the piece. --Jeffrey.
            [Shields] with boastful argument portrayed.
                                                  --Milton.
   5. Matter for question; business in hand. [Obs.]
            Sheathed their swords for lack of argument. --Shak.
   6. (Astron.) The quantity on which another quantity in a
      table depends; as, the altitude is the argument of the
      refraction.
   7. (Math.) The independent variable upon whose value that of
      a function depends. --Brande & C.
   

2. \Ar"gu*ment\ ([a^]r"g[-u]*ment), v. i. [L.
   argumentari.]
   To make an argument; to argue. [Obs.] --Gower.
   

(Or "arg") A value or reference passed to a function, procedure, subroutine, command or program, by the caller. For example, in the function

        square(x) = x * x

x is the formal argument or "parameter" and in the call

        y = square(3+3)

3+3 is the actual argument. This will, in most cases, execute the function square with x having the value 6.

There are many different conventions for passing arguments to functions and procedures including call-by-value, call-by-name, call-by-need. These affect whether the value of the argument is computed by the caller or the callee (the function) and whether the callee can modify the value of the argument as seen by the caller (if it is a variable).

Arguments to functions are usually, following mathematical notation, written in parentheses after the function name, separated by commas. Arguments to a program are usually given after the command name, separated by spaces, e.g.:

        cat myfile yourfile hisfile

Here "cat" is the command and "myfile", "yourfile", and "hisfile" are the arguments.

See also: curried function.