A common suffix used to indicate a 'madness' -- specifically a pathology in which one is abnormally obsessed or fixated on something. For example, bibliomania is an obsessive fixation on books. It is used jokingly or informally as often as it is in seriousness. Some 'real' manias include nymphomania, dipsomania, kleptomania, and megalomania.

There is very little standardization in the coinage of psychological terms, and so there are other suffixes used in much the same way as -mania. The suffix -philia (meaning 'love') may also be used, particularly if the madness exhibits itself as sexual arousal, as in Kleptophilia. The suffix -phobia will be used if the fixation exhibits itself as a fear. The German translation of -mania is -sucht, so you will occasionally come across manias such as witzelsucht and grubelsucht. There are also a handful of manias that have somewhat random names, such as zoanthropy and gambling addiction (although the later may be called ludomania if you are a onomamaniac).

Mania may be used as a stand-alone noun, although in common psychological usage the noun 'mania' refers specifically to an abnormally elevated mood, irritable mood, or a high energy level (and in the 'maniac' side of bipolar disorder), so should be used with that in mind. One suffering from a mania is a maniac, and -maniac may also be used as a suffix, as in kleptomaniac.

It comes from the Greek mania, meaning 'madness' or 'frenzy'; it was also used in the less dire sense (as it is to this day), to indicate enthusiasm or passion for a subject.