It is one of the most emotive and sensitive subjects in British politics.
But at times it seems there are as many definitions of multiculturalism as there are columnists, experts and intellectuals prepared to weigh into the debate.
The subject has become the focus of renewed scrutiny in the wake of a speech by prime minister David Cameron, in which he told a security conference in Germany that the UK needed a stronger national identity to prevent extremism.
In his speech, which has provoked a political storm, Mr Cameron defines "the doctrine of state multiculturalism" as a strategy which has "encouraged different cultures to live separate lives, apart from each other and apart from the mainstream".
This characterisation is not new. In 2004 Trevor Phillips, chairman of the the Commission for Racial Equality - now the Equality and Human Rights Commission - told the Times that multiculturalism was out of date because it "suggests separateness" and should be replaced with policies which promote integration and "assert a core of Britishness".
But is everyone who uses the term referring to the same phenomenon?
Academics' definitions of multiculturalism refer to anything from people of different communities living alongside each other to ethnic or religious groups leading completely separate lives.
Likewise, columnists who write about multiculturalism don't often define what they mean by the term, looking instead at what it is not.
The Oxford English Dictionary offers a broad definition of multiculturalism as the "characteristics of a multicultural society" and "the policy or process whereby the distinctive identities of the cultural groups within such a society are maintained or supported".