If a person says in English the word g-ddamn (or G-d damn) does that transgress the sin of cursing God?
No, it does not.
"Cursing" someone in a Biblical sense means saying "may G-d strike you." Thus a person would only be liable for cursing their parent if they said "may G-d strike you" to their parent.
When someone says "I hit my thumb with this G-ddamn hammer!", an English professor would tell you that means "may G-d damn this hammer because I am mad at it." In effect you are cursing the hammer. It may be a wasted use of G-d's name, but it's not "blasphemy" per se. (Many people today might actually intend "this G-ddamned hammer", i.e. "I assume G-d has already cursed this hammer", which means you're not cursing anything with your statement. Just like calling something "G-dforsaken.")
The Talmud (Sanhedrin 56a) explains that the only form of true "blasphemy", as described in Leviticus 24:15, would then be to curse G-d in a biblical sense, i.e. to say "may Joe strike Joe" (or "may Joe damn Joe", for that matter), substituting "G-d" for Joe. (Which is a bit strange, if someone doesn't believe in G-d, why they're calling on Him to smite anything, but never mind.) Maimonides, Laws of Foreign Worship 2:7 discusses the severity of punishment may depend on exactly which name of G-d is used, but in conclusion:
- "G-ddamn it", "this G-ddamn hammer", and the like are wasteful uses of G-d's name and should be avoided, but are not "cursing G-d" or "blasphemy."
- Do not direct a "G-ddamn you" towards any person; especially not towards your parent; and definitely not towards G-d.