Source : Webster's Revised Unabridged Dictionary (1913)

Pathologic \Path`o*log"ic\, Pathological \Path`o*log"ic*al\, a.
   (Med.)
   Morbid; due to disease; abnormal; as, pathological tissue; a
   pathological condition.

Pathologic \Path`o*log"ic\, Pathological \Path`o*log"ic*al\, a.
   [Gr. ?: cf. F. pathologique.]
   Of or pertaining to pathology. -- {Path`o*log"ic*al*ly}, adv.

Source : WordNet®

pathological
     adj 1: of or relating to the practice of pathology; "pathological
            laboratory" [syn: {pathologic}]
     2: caused by or evidencing a mentally disturbed condition; "a
        pathological liar"; "a pathological urge to succeed"
     3: caused by or altered by or manifesting disease or pathology;
        "diseased tonsils"; "a morbid growth"; "pathologic
        tissue"; "pathological bodily processes" [syn: {diseased},
         {morbid}, {pathologic}]

Source : Free On-Line Dictionary of Computing

pathological
     
        1. [scientific computation] Used of a data set that is grossly
        atypical of normal expected input, especially one that exposes
        a weakness or bug in whatever algorithm one is using.  An
        algorithm that can be broken by pathological inputs may still
        be useful if such inputs are very unlikely to occur in
        practice.
     
        2. When used of test input, implies that it was purposefully
        engineered as a worst case.  The implication in both senses is
        that the data is spectacularly ill-conditioned or that someone
        had to explicitly set out to break the algorithm in order to
        come up with such a crazy example.
     
        3. Also said of an unlikely collection of circumstances.  "If
        the network is down and comes up halfway through the execution
        of that command by root, the system may just crash."  "Yes,
        but that's a pathological case."  Often used to dismiss the
        case from discussion, with the implication that the
        consequences are acceptable, since they will happen so
        infrequently (if at all) that it doesn't seem worth going to
        the extra trouble to handle that case (see sense 1).
     
        [{Jargon File}]