Pundits have been reacting to a speech by David Cameron in which the prime minister argued multiculturalism had "failed". But what do commentators actually mean by the term?
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for Racial Equality - now the Equality and Human Rights Commission - told the Times that multiculturalism was out of date because it "suggests separateness" and should be replaced with policies which promote integration and "assert a core of Britishness".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".
Lord Sacks, Chief Rabbi of the United Hebrew Congregations of the Commonwealth says in the Times that multiculturalism was intended to create a more tolerant society, one in which everyone, regardless of colour, creed or culture, felt at home. But, he says, multiculturalism's message is "there is no need to integrate".
He distinguishes between tolerance and multiculturalism - using the Netherlands as an example of a tolerant, rather than multicultural, society.
Additionally, he says the current meaning of multiculturalism is part of the wider European phenomenon of moral relativism and talks of multiculturalism as dissolving national identity, shared values and collective identity which "makes it impossible for groups to integrate because there is nothing to integrate into".
Others, however, see the term as offering a range of meanings. In the Observer, the editor of Prospect magazine, David Goodhart, insists the strategy has taken on different forms within the UK over the years.
He distinguishes between the "live and let live" multiculturalism of the 1950s, which "assumed that if people could keep significant aspects of their culture they would choose to integrate in their own way"; the 1980s "'soft' multiculturalism of tolerance and equal rights"; and the more recent "hard" multiculturalism "of positive promotion of religious and ethnic identities".
Rod Liddle says in the Spectator that multiculturalism is a notion that cultures, no matter how antithetical to the norm, or anti-social, should be allowed to develop unhindered, without criticism.
Melanie Phillips takes this argument further in the Daily Mail, arguing that multiculturalism is a form of reverse-racism and "sickeningly hypocritical".
However, Madeleine Bunting of the Guardian says Mr Cameron has offered "a straw man version of multiculturalism". Instead of promoting segregation, she says, it is "a matter of pragmatism" - reaching out to organisations within ethnic communities who can help the government achieve its goals of maintaining good community relations.
In the same newspaper in March 2010, Antony Lerman, a former director of the Institute for Jewish Policy Research, pointed to some of the academic work on multiculturalism to show it is the opposite of a philosophy of separateness. He cited Professor Bhikhu Parekh's definition which says, far from "putting people into ethnic boxes", multiculturalism is a "fusion in which a culture borrows bits of others and creatively transforms both itself and them".
Professor Tariq Modood is director of the Centre for Study of Ethnicity and Citizenship at the University of Bristol and wrote Still Not Easy Being British: Struggles for a Multicultural Citizenship. He says in a Runnymede Trust web chat that multiculturalism has many meanings, but the minimum is the need to politically identify groups, typically by ethnicity, and to work to remove stigmatisation, exclusion and domination in relation to such groups.
The debate around multiculturalism may be an important one. But while public discussion of the subject may have become more familiar, there remains little consensus about what the word actually means.