curse - nope, that's only an invocation of bad fate upon somebody; there are other forms of "psovka" which do not involve "may you". Many times it takes a form of past tense meaning future (as in "I [will] have fucked your mother")
cuss - that's primarily a person, and secondarily foul language, so it doesn't mean "psovka"
expletive - is a term in grammar, and an adjective on top of it, not a noun per se.
swearword - not applicable, a "psovka" is usually a whole sentence, or a phrase
bad language - not applicable either, it's an euphemism, while "psovka" is exactly the unambiguous term to denote the foul thing being said.
oath - can be confused with a solemn oath, a vow, while "psovka" is... well, can't express that in english.