Source : Webster's Revised Unabridged Dictionary (1913)

Reasoning \Rea"son*ing\, n.
   1. The act or process of adducing a reason or reasons; manner
      of presenting one's reasons.

   2. That which is offered in argument; proofs or reasons when
      arranged and developed; course of argument.

            His reasoning was sufficiently profound. --Macaulay.

   Syn: Argumentation; argument.

   Usage: {Reasoning}, {Argumentation}. Few words are more
          interchanged than these; and yet, technically, there
          is a difference between them. Reasoning is the broader
          term, including both deduction and induction.
          Argumentation denotes simply the former, and descends
          from the whole to some included part; while reasoning
          embraces also the latter, and ascends from a part to a
          whole. See {Induction}. Reasoning is occupied with
          ideas and their relations; argumentation has to do
          with the forms of logic. A thesis is set down: you
          attack, I defend it; you insist, I prove; you
          distinguish, I destroy your distinctions; my replies
          balance or overturn your objections. Such is
          argumentation. It supposes that there are two sides,
          and that both agree to the same rules. Reasoning, on
          the other hand, is often a natural process, by which
          we form, from the general analogy of nature, or
          special presumptions in the case, conclusions which
          have greater or less degrees of force, and which may
          be strengthened or weakened by subsequent experience.

Reason \Rea"son\, v. t. [imp. & p. p. {Reasoned}; p. pr. & vb.
   n. {Reasoning}.] [Cf. F. raisonner. See {Reason}, n.]
   1. To exercise the rational faculty; to deduce inferences
      from premises; to perform the process of deduction or of
      induction; to ratiocinate; to reach conclusions by a
      systematic comparison of facts.

   2. Hence: To carry on a process of deduction or of induction,
      in order to convince or to confute; to formulate and set
      forth propositions and the inferences from them; to argue.

            Stand still, that I may reason with you, before the
            Lord, of all the righteous acts of the Lord. --1
                                                  Sam. xii. 7.

   3. To converse; to compare opinions. --Shak.

Source : WordNet®

reasoning
     adj : endowed with the capacity to reason [syn: {intelligent}, {reasoning(a)},
            {thinking(a)}]

reasoning
     n : thinking that is coherent and logical [syn: {logical
         thinking}, {abstract thought}]