Firefox is removing terminology from the browser that has been identified as derogatory or exclusionary. We’re listening to conversations happening within the Mozilla community and in the world at large, and are paying attention when people tell us that some terms we use in Firefox exclude and damage people.
‘Master-slave’ is a metaphor that perpetuates racism. Firefox strives for inclusion and clarity; we have no need for terms derived from harmful metaphors when we have plenty of alternatives that are more inclusive, more descriptive and non-racist. For this reason, all instances of Master Password are being replaced with Primary Password in the Firefox browsers and products.
Deprecating the term Master Password is also in accordance with the "Derogatory Language" section of the Mozilla Community Participation Guidelines.