I say "white man" to capture an ethnicity, not a race. Anglo-Euros with empires and slavery to justify, and control over the curriculum namespaces.
There's no "race gene" that divides 1/2, 1/4, 1/8... such that "by blood, I'm 1/32nd Black" -- that's utter nonsense, dumbed down to fit the arithmetic of an elementary school teacher. To this day, Anglo-Euros strut about talking about "race" as if it meant something, failing to see "ethnicity" as what they're really talking about. They don't get a decent semantics in school, and flounder and drown (figuratively) in their own poorly designed concepts. A racist is someone who believes in races.
A big diff between "race" and "ethnicity" is the former is imposed on you by authorities, who may insist you go by "mixed" whether or not you believe in their faux taxonomy. They won't let you "pass" as white if you're 1/32nd "black" or whatever ethnic nazi apartheid garbage they go by.
"Ethnicity" on the other hand is something I have more control over, even more than over gender it would seem to me (I can't change my XY to the XX of the stronger sex). I may be born into one ethnicity, yet die in another. Indeed, I'm able to tell people (versus be told) what my ethnicity is, and the vocabulary there is always changing.