Real Dictionary

partisan
Someone who is partisan strongly supports a particular person or cause, often without thinking carefully about the matter.

partisan in American English 1
a person who takes the part of or strongly supports one side, party, or person; often, specif., an unreasoning, emotional adherent
of, like, or characteristic of a partisan
adjective: of, pertaining to, or characteristic of partisans; partial to a specific party, person, etc
noun: an adherent or supporter of a person, group, party, or cause, esp. a person who shows a biased, emotional allegiance

partisan in American English 2
a broad-bladed weapon with a long shaft, used esp. in the 16th cent.
noun: a shafted weapon of the 16th and 17th centuries, having as a head a long spear blade with a pair of curved lobes at the base

partisan in British English 1
adjective: of, relating to, or characteristic of a partisan
noun: an adherent or devotee of a cause, party, etc

partisan in British English 2
noun: a spear or pike with two opposing axe blades or spikes