Definitions of mania on the Web:

• an irrational but irresistible motive for a belief or action
  
• a mood disorder; an affective disorder in which the victim tends to respond excessively and sometimes violently
  wordnet.princeton.edu/perl/webwn
• Mania describes a medical condition characterised by severely elevated mood. Mania is most usually associated with bipolar disorder, where episodes of mania may cyclically alternate with episodes of depression. (Note: not all mania can be classified as bipolar disorder as mania may result from other diseases or causes. mania - however bipolar disorder is the 'classic' manic disease).
  en.wikipedia.org/wiki/Mania
• The English suffix -mania denotes an obsession or madness towards something; a mania. The suffix is used in some medical terms denoting mental disorders. It has also entered standard English and is affixed to many different words to denote enthusiasm or obsession with that subject.
  en.wikipedia.org/wiki/-mania
• In Greek mythology, Mania ("insanity") was the personification of insanity.
  en.wikipedia.org/wiki/Mania_(mythology)
• A mood disorder characterized by excessive elation or irritability, hyperactivity, poor concentration and accelerated thinking and speaking, and resulting in impaired judgement. Mania is seen in major disorders involving disturbance of mood and in organic mental disorders.(return to top)
  www.longislandpsych.org/PatientRes/ImptTerms/ImptTerms.html
• a mood disorder which may be characterized by extreme elation, impulsivity, irritability, rapid speech, nervousness, distractibility, and/or poor judgment.
  www.frankfordhospitals.org/healthinfo/adult/mentalhealth/glossary.html
• An emotional disorder characterized by euphoria or irritability, rapid speech, fleeting thoughts, insomnia, poor attention span, grandiosity, and poor judgment; usually occurs in bipolar disorder. Positive symptoms of psychosis may also be present.
  www.indianpsychiatry.com/Glossary.htm
• A state of extreme overactivity and high mood. It is seen as the opposite of depression. See our leaflets on Manic Depression (Bipolar Disorder) and Medications for Mania for further information.
  www.rcpsych.ac.uk/info/glosConds.htm
• Period of behavior characterized by predominantly elevated, expansive mood, either euphoric or irritable, with a duration of at least one week. Accompanying behaviors may include increased activity, restlessness, talkativeness, flight of ideas, feeling of racing thoughts, grandiosity, decreased sleep time, short attention span, buying sprees, sexual indiscretion, and inappropriate laughing, joking, or punning.
  www.dphilpotlaw.com/html/glossary.html
• popular name of insanity; in psychiatry, as a science, it means a state of lifted spirits and anxiety
  library.thinkquest.org/C0115926/glosary.htm
• a mental disorder characterized by extreme excitement, happiness, overactivity, and agitation; usually refers to the high of the highs and lows experienced in manic-depressive disorder
  www.american-depot.com/services/resources_gl_m.asp
• means a mental disorder that involves extreme optimism and excessive energy, often accompanied by uncontrollable irritability and anger.
  www.a2zpsychology.com/psychology_guide/mental_illness_terminology.htm
• Usually occurs as a phase of bipolar disorder. Attacks first appear before age 30. Key symptoms: abnormally over-active and energetic, impulsive, elated, grandiose, outbursts of inappropriate irritation, anger, laughter, rapid pressured speech, being ‘everybody’s friend." May spend money recklessly. Judgment of what is harmful to the subject is impaired. Severe mania lasts from a few days to several months and if untreated, may lead to social disruption and violence.
  www.jibc.bc.ca/police/main/PIIMIC/Glossary/glossary/m.htm
• A mood disorder characterized by an intense feeling of elation or irritability and rapidly changing moods (mood lability), often accompanied by increased activity, rapid speech or distractibility.
  www.schizophrenicpen.com/def2.html
• A mental disorder characterized by excessive excitement. A form of psychosis with exalted feelings, delusions of grandeur, elevated mood, psychomotor over-activity and overproduction of ideas.
  www.mindsci-clinic.com/neuro_jargon.htm

Taken from Google