I previously posted my worries about the glossary entry for the word 'gay' in Elizabeth Meyer's Gender, Bullying, and Harassment. I'm worried about the following entry also, for several reasons:
Heterosexism: A bias toward heterosexuality that denigrates and devalues GLB people. Also, the presumption that heterosexuality is superior to homosexuality or prejudice, bias, or discrimination based on these things.
The first thing to notice is that this is a disjunctive definition. It lists three different things, any of which it will count as heterosexism. This isn't problematic in itself. There are plenty of words that can apply to a number of different things. Some of them are due to plain old ambiguity, e.g. the word 'bank' can mean a financial institution or the sandy shoreline alongside a river. More often a term can refer to several phenomena that all fit under the same category.
What might generate more of a problem is when a term is defined to refer to a number of different phenomena that are sufficiently different and should not be confused with each other. This isn't necessarily a problem, though. For instance, there are plenty of things the word 'homicide' can refer to, and they've of a pretty diverse sort. A homicide could be a cold-blooded, premeditated murder, or it could be an unplanned violent killing in the heat of an argument. It could be criminal but accidental manslaughter, or it could be excusable self-defense. In all cases, someone has been killed, and thus it counts as a homicide, which etymologically and in actual contemporary usage simply means the killing of a person by someone else.
Where it becomes more problematic is if the word you choose to use for this is loaded in such a way that its very usage carries the sense that anything it applies to is equally wrong. This is a new enough term that I think it's fair to say that people who are using it as Meyer does are in fact in the process of coining the term and determining its meaning by how it's used. The fact that it's deliberately a parallel with words like 'sexism' and 'racism' is important here. I suspect Meyer, and those whose consensus she wants to represent in her glossary of how such terms are used, wants all three things she lists to be seen as serious as racism and sexism are. The problem is that a case can be made that they're not. Let's separate the different meanings.
A: A bias toward heterosexuality that denigrates and devalues GLB people
B: the presumption that heterosexuality is superior to homosexuality
C: prejudice, bias, or discrimination based on these things.
It seems to me that anyone satisfying meaning A is engaging in pure evil, but meanings B and C can range over a wide enough range of things that they don't belong in the same category at all. Some of that wide range is clearly morally problematic (perhaps stemming from something like what meaning A is getting at). Some of it is simply a matter of empirical discovery, but some of it involves moral judgment.