Source : Webster's Revised Unabridged Dictionary (1913)

Logic \Log"ic\, n. [OE. logike, F. logique, L. logica, logice,
   Gr. logikh` (sc. te`chnh), fr. logiko`s belonging to speaking
   or reason, fr. lo`gos speech, reason, le`gein to say, speak.
   See {Legend}.]
   1. The science or art of exact reasoning, or of pure and
      formal thought, or of the laws according to which the
      processes of pure thinking should be conducted; the
      science of the formation and application of general
      notions; the science of generalization, judgment,
      classification, reasoning, and systematic arrangement;
      correct reasoning.

Source : WordNet®

logic
     n 1: the branch of philosophy that analyzes inference
     2: reasoned and reasonable judgment; "it made a certain kind of
        logic"
     3: the principles that guide reasoning within a given field or
        situation; "economic logic requires it"; "by the logic of
        war"
     4: a system of reasoning [syn: {logical system}, {system of
        logic}]

Source : Free On-Line Dictionary of Computing

logic
     
        1.  A branch of philosophy and
        mathematics that deals with the formal principles, methods and
        criteria of validity of {inference}, reasoning and
        {knowledge}.
     
        Logic is concerned with what is true and how we can know
        whether something is true.  This involves the formalisation of
        logical arguments and {proof}s in terms of symbols
        representing {proposition}s and {logical connective}s.  The
        meanings of these logical connectives are expressed by a set
        of rules which are assumed to be self-evident.
     
        {Boolean algebra} deals with the basic operations of truth
        values: AND, OR, NOT and combinations thereof.  {Predicate
        logic} extends this with existential and universal
        {quantifier}s and symbols standing for {predicate}s which may
        depend on variables.  The rules of {natural deduction}
        describe how we may proceed from valid premises to valid
        conclusions, where the premises and conclusions are
        expressions in {predicate logic}.
     
        Symbolic logic uses a {meta-language} concerned with truth,
        which may or may not have a corresponding expression in the
        world of objects called existance.  In symbolic logic,
        arguments and {proof}s are made in terms of symbols
        representing {proposition}s and {logical connective}s.  The
        meanings of these begin with a set of rules or {primitive}s
        which are assumed to be self-evident.  Fortunately, even from
        vague primitives, functions can be defined with precise
        meaning.
     
        {Boolean logic} deals with the basic operations of {truth
        value}s: AND, OR, NOT and combinations thereof.  {Predicate
        logic} extends this with {existential quantifier}s and
        {universal quantifier}s which introduce {bound variable}s
        ranging over {finite} sets; the {predicate} itself takes on
        only the values true and false.  Deduction describes how we
        may proceed from valid {premise}s to valid conclusions, where
        these are expressions in {predicate logic}.
     
        Carnap used the phrase "rational reconstruction" to describe
        the logical analysis of thought.  Thus logic is less concerned
        with how thought does proceed, which is considered the realm
        of psychology, and more with how it should proceed to discover
        truth.  It is the touchstone of the results of thinking, but
        neither its regulator nor a motive for its practice.
     
        See also fuzzy logic, logic programming, arithmetic and logic unit,
        first-order logic,
     
        See also {Boolean logic}, {fuzzy logic}, {logic programming},
        {first-order logic}, {logic bomb}, {combinatory logic},
        {higher-order logic}, {intuitionistic logic}, {equational
        logic}, {modal logic}, {linear logic}, {paradox}.
     
        2.  {Boolean} logic circuits.
     
        See also {arithmetic and logic unit}, {asynchronous logic},
        {TTL}.
     
        (1995-03-17)