Sentence:  Being vulnerable as an official language minority within the Canadian federation, the Québec francophones thus reaffirmed their commitment to the values of pluralism and diversity while also taking measures to prevent the worsening, through the anglicization of immigrants, of the existing historical <WSD>linguistic imbalance</WSD> within Canada. 
Meaning of the word marked with <WSD> tags:  The levels of official use or representation of languages that are perceived not to reflect their use in the population.