To be fair, the "feminist" movement has been undergoing a bit of evolution (or devolution depending on which facet you choose to look at) and that simple definition doesn't really fit all of it anymore. To pick a completely random example in order to better illustrate what I mean, "trolling" used to mean a specific method of trying to irritate people using logical fallacies, but now it encompasses much more than was originally intended and is used to describe everything up to and including just being an asshole.
I know this has already been postulated, but are we talking about those who believe that women deserve the same rights as men, or are we talking about people like the retards on Shit Reddit Says (SRS)? If we're all thinking about different definitions of feminism, this conversation won't get anywhere.
...Back to lurking.
I don't think that definition has EVER fit "all of it." Like many ideologies, feminism has a whole bunch of sub-factions and they can sometimes be at odds with each other, and I think that's been true for a pretty long time (in the West probably at least since some basic freedoms were won e.g. voting and owning property- since before then, everyone who might have aligned themselves with a faction within feminism tried to unite to get that shit done). Half the world's population is women and treatment of women varies widely from culture to culture, so what any specific group of feminists are reacting to will inform their ideology. Even within a single culture there are factions- in the US you've got your sex-positive feminists, socialist feminists, family-oriented feminists (that would be me), ecofeminists, intersectional feminists (that would also be me), and that's just the ones I can think of off the top of my head before I got tired of thinking about it.
Here are two definitions of feminism from people who are pretty closely linked to various arms of the movement themselves:
Gloria Steinem:
"The belief in full economic political and social equality of males and females . . . usually seen as a modern movement to transform the male-dominant past and create an egalitarian future. On this and other continents, however, feminism is also history and even memory"
Barbara Smith and Gwendolyn Mink (not as recognizable outside of feminism, but inside scholarly feminism they are pretty ubiquitous):
"Feminism articulates political opposition to the subordination of women as women, whether that subordination is ascribed by law, imposed by social convention, or inflicted by individual men and women. Feminism also offers alternatives to existing unequal relations of gender power, and these alternatives have formed the agenda for feminism movements"