The Collaborative International Dictionary of English v.0.48:

Mania \Ma"ni*a\, n. [L. mania, Gr. ?, fr. ? to rage; cf. OE.
   manie, F. manie. Cf. Mind, n., Necromancy.]
   1. Violent derangement of mind; madness; insanity. Cf.
      Delirium.
      [1913 Webster]

   2. Excessive or unreasonable desire; insane passion affecting
      one or many people; as, the tulip mania.
      [1913 Webster]

   Mania a potu [L.], madness from drinking; delirium tremens.
      [1913 Webster]

   Syn: Insanity; derangement; madness; lunacy; alienation;
        aberration; delirium; frenzy. See Insanity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

mania
    n 1: an irrational but irresistible motive for a belief or
         action [syn: mania, passion, cacoethes]
    2: a mood disorder; an affective disorder in which the victim
       tends to respond excessively and sometimes violently [syn:
       mania, manic disorder]

Moby Thesaurus II by Grady Ward, 1.0:

129 Moby Thesaurus words for "mania":
   aberration, abnormality, abstraction, abulia, alienation,
   an universal wolf, anxiety, anxiety equivalent, anxiety state,
   apathy, appetence, appetency, appetite, appetition, brain damage,
   brainsickness, bug, catatonic stupor, clouded mind, compulsion,
   coveting, craving, craze, craziness, crazy fancy, daftness,
   dejection, dementedness, dementia, depression, derangement, desire,
   detachment, disorientation, distraction, elation, emotionalism,
   enthusiasm, euphoria, fad, fanaticism, fancy, fascination,
   fixation, fixed idea, folie, folie du doute, frenzy, furor, furore,
   fury, hangup, hunger, hypochondria, hysteria, hysterics, idee fixe,
   indifference, infatuation, insaneness, insanity, insensibility,
   irrationality, itch, itching, lethargy, loss of mind,
   loss of reason, lunacy, madness, manic-depressive psychosis,
   melancholia, mental deficiency, mental derangement, mental disease,
   mental disorder, mental distress, mental disturbance,
   mental illness, mental instability, mental sickness,
   mind overthrown, mindsickness, obsession, oddness,
   overambitiousness, overanxiety, overanxiousness, overeagerness,
   overenthusiasm, overzealousness, passion,
   pathological indecisiveness, pixilation, possession, preoccupation,
   prurience, pruriency, psychalgia, psychomotor disturbance,
   queerness, rabidness, rage, reasonlessness, senselessness,
   sexual desire, shattered mind, sick mind, sickness, strangeness,
   stupor, thing, thirst, tic, twitching, unbalance, unbalanced mind,
   unresponsiveness, unsaneness, unsound mind, unsoundness,
   unsoundness of mind, urge, withdrawal, witlessness, yearning, yen,
   zealotism, zealotry



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MANIA, med. jur. This subject will be considered by examining it, first, in
a medical point of view; and, secondly, as to its legal consequences.
     2.-Sec. 1. Mania may be divided into intellectual and moral.
     1. Intellectual mania is that state of mind which is characterised by
certain hallucinations, in which the patient is impressed with the reality
of facts or events which have never occurred, and acts in accordance with
such belief; or, having some notion not altogether unfounded, carries it to
an extravagant and absurd length. It may be considered as involving all or
most of the operations of the understanding, when it is said to be general;
or as being confined to a particular idea, or train of ideas, when it is
called partial.
     3. These will be separately examined. 1st. General intellectual mania
is a disease which presents the most chaotic confusion into which the human
mind, can be involved, and is attended by greater disturbance of the
functions of the body than any other. According to Pinel, Traite
d'Alienation Mentale, p. 63, "The patient sometimes keeps his head elevated
and his looks fixed on. high; he speaks in a low voice, or utters cries and
vociferations without any apparent motive; he walks to and fro, and
sometimes arrests his steps as if fixed by the sentiment of admiration, or
wrapt up in profound reverie. Some insane persons display wild excesses of
merriment, with immoderate bursts of laughter. Sometimes also, as if nature
delighted in contrasts, gloom and taciturnity prevail, with involuntary
showers of tears, or the anguish of deep sorrow, with all the external signs
of acute mental suffering. In certain cases a sudden reddening of the eyes
and excessive loquacity give presage of a speedy explosion of violent
madness and the urgent necessity of a strict confinement. One lunatic, after
long intervals of calmness, spoke at first with volubility, uttered frequent
shouts of laughter, and then shed a torrent of tears; experience had taught
the necessity of shutting him up immediately, for his paroxysms were at such
times of the greatest violence. "Sometimes, however, the patient is not
altogether devoid of intelligence; answers some questions very
appropriately, and is not destitute of acuteness and ingenuity. The
derangement in this form of mania is not confined to the intellectual
faculties, but not unfrequently extends to the moral powers of the mind.
     4.-2d. Partial intellectual mania is generally known by the name of
monomania. (q.v.) In its most usual and simplest form, the patient has
conceived some single notion contrary to common sense and to common
experience, generally dependent on errors of sensation; as, for example,
when a person believes that he is made of glass, that animals or men have
taken their abode in his stomach or bowels. In these cases the understanding
is frequently found to be sound on all subjects, except those connected with
the hallucination. Sometimes, instead of being limited to a single point,
this disease takes a wider range, and there is a class of cases, where it
involves a train of morbid ideas. The patient then imbibes some notions
connected with the various relations of persons, events, time, space, &c.,
of the most absurd and unfounded nature, and endeavors, in some measure, to
regulate his conduct accordingly; though, in most respects, it is grossly
inconsistent with his delusion.
     5. Moral mania or moral insanity, (q.v.) is divided into, first,
general, where all the moral faculties are subject to a general disturbance
and secondly, partial, where one or two only of the moral powers are
perverted.
     6. These will be briefly and separately examined. 1st. It is certain
that many individuals are living at large who are affected, in a degree at
least, by general moral mania. They are generally of singular habits,
wayward temper, and eccentric character; and circumstances are frequently
attending them which induce a belief that they are not altogether sane.
Frequently there is a hereditary tendency to madness in the family; and, not
seldom, the individual himself has at a previous period of life sustained an
attack of a decided character: his temper has undergone a change, he has
become an altered man, probably from the  time of the occurrence of
something which deeply affected him, or which deeply affected his bodily
constitution. Sometimes these alterations are imperceptible, at others, they
are sudden and immediate. Individuals afflicted with this disease not
unfrequently "perform most of the common duties of life with propriety, and
some of them, indeed, with scrupulous exactness, who exhibit no strongly
marked features of either temperament, no traits of superior or defective
mental endowment, but yet take violent antipathies, harbor unjust
suspicions, indulge strong propensities, affect singularity in dress, gait,
and phraseology; are proud, conceited, and ostentatious; easily excited and
with difficulty appeased; dead to sensibility, delicacy, and refinement;
obstinately riveted to the most absurd opinions; prone to controversy, and
yet incapable of reasoning; always the hero of their own tale, using
hyperbolic, high flown language to express the most simple ideas,
accompanied by unnatural gesticulation, inordinate action, and frequently by
the most alarming expression of countenance. On some occasions they suspect
sinister intentions on the most trivial grounds; on others are a prey to
fear and dread from the most ridiculous and imaginary sources; now embracing
every opportunity of exhibiting romantic courage and feats and hardihood,
then indulging themselves in all manner of excesses. Persons of this
description, to the casual observer, might appear actuated by a bad heart,
but the experienced physician knows it is the head which is defective. They
seem as if constantly affected by a greater or less degree of stimulation
from intoxicating liquors, while the expression of countenance furnishes an
infallible proof of mental disease. If subjected to moral restraint, or a
medical regimen, they yield with reluctance to the means proposed, and
generally refuse and resist, on the ground that such means are unnecessary
where no disease exists; and when, by the system adopted, they are so far
recovered, as to be enabled to suppress the exhibition of their former
peculiarities, and are again fit to be restored to society, the physician,
and those friends who put them under the physician's care, are generally
ever after objects of enmity, and frequently of revenge." Cox, see cases of
this Pract. Obs. on Insanity, kind of madness cited in Ray, Med. Jur. Sec.
112 to 119; Combe's Moral Philos. lect. 12.
     7.-2d. Partial moral mania consists in the derangement of one or a
few of the affective faculties, the moral and intellectual constitution in
other respects remaining in a sound state. With a mind apparently in full
possession of his reason, the patient commits a crime, without any
extraordinary temptation, and with every inducement to refrain from it, he
appears to act without a motive, or in opposition to one, with the most
perfect consciousness of the impropriety, of his conduct, and yet he pursues
perseveringly his mad course. This disease of the mind manifests itself in a
variety of ways, among which may be mentioned the following: 1. An
irresistible propensity to steal. 2. An inordinate propensity to lying. 3. A
morbid activity of the sexual propensity. Vide Erotic Mania. 4. A morbid
propensity to commit arson. 5. A morbid activity of the propensity to
destroy. Ray, Med. Jur. ch. 7.
     8.-Sec. 2. In general, persons laboring under mania are not
responsible nor bound for their acts like other persons, either in their
contracts or for their crimes, and their wills or testaments are voidable.
Vide Insanity; Moral Insanity. 2 Phillim. Eccl. R. 69; 1 Hagg. Cons: R. 414;
4 Pick. R. 32; 3 Addams, R. 79; 1 Litt. R. 371.