/ ˌkəʊəˈlɪʃn; NAmE ˌkoʊə-/ noun
1.
[ C +sing./pl. v . ] a government formed by two or more political parties working together :
to form a coalition
a two-party coalition
a coalition government
2.
[ C +sing./pl. v . ] a group formed by people from several different groups, especially political ones, agreeing to work together for a particular purpose :
a coalition of environmental and consumer groups
3.
[ U ] the act of two or more groups joining together :
They didn't rule out coalition with the Social Democrats.
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WORD ORIGIN
early 17th cent. (in the sense fusion ): from medieval Latin coalitio(n-) , from the verb coalescere grow together, from co- (from cum with) + alescere grow up. Usage in politics dates from the late 18th cent.