adjective
(chiefly British Isles) Insane; crazy, mentally deranged.
(chiefly US; informal in UK and Ireland) Angry, annoyed.
(chiefly in the negative, informal) Used litotically to indicate satisfaction or approval.
(UK, Ireland, informal) Bizarre; incredible.
Wildly confused or excited.
Extremely foolish or unwise; irrational; imprudent.
(colloquial, usually with for or about) Extremely enthusiastic about; crazy about; infatuated with; overcome with desire for.
(of animals) Abnormally ferocious or furious; or, rabid, affected with rabies.
(slang, chiefly New York, African-American Vernacular) Intensifier, signifying abundance or high quality of a thing; very, much or many.
(of a compass needle) Having impaired polarity.
adverb
(slang, chiefly New York, African-American Vernacular, UK and Ireland, dialectal) Intensifier; to a large degree; extremely; exceedingly; very; unbelievably.
verb
(obsolete, intransitive) To be or become mad.
(now colloquial US, Jamaica) To madden, to anger, to frustrate.