American defines d*mn, f-word and b-word (excuse my language) as curse words. However, what does the Torah define as curse words or dirty language?
Technically speaking, there is no concept in halacha of a word which simply cannot be used under any circumstances (with the partial exception of God's name). The furthest Jewish law in this regard is to encourage using a 'cleaner' way of expressing an idea if this is as efficient as the less 'clean' manner. The Talmud (Pesachim 3b) states, "Whenever they are equal, use the clean language; whenever one uses more words, use the shorter language". "Clean" in this context is a very broad idea; even simply referring to a pig or a lizard unnecessarily can be considered unclean.
There is, however, another issue which is much more serious. This involves the prohibition of nivul peh - lascivious talk. Speaking about sexuality in an inappropriate manner is a very serious sin. The Talmud states (Shabbos 33a):
For the sin of nivul peh many troubles and harsh decrees arise, the young men of (the enemies of) Israel die, orphans and widows cry out and are not answered, as [Isaiah 9:16] says, "Therefore God has no happiness from his young men, and He has no mercy on his orphans and his widows, for they all flatter and do evil, and every mouth is full of obscenity; due to all this His anger is not turned away and His hand is still outstretched." What does "His hand is still outstretched" mean? Rabbi Chanan son of Rava said, "Everyone knows why a bride enters the bridal canopy, but anyone who speaks obscenely (i.e. speaks out the reason), even if they (the Heavenly Court) had signed a decree of seventy years of goodness for him, it is turned to bad." Rabbi Chisda said, "Anyone who speaks obscenely, they deepen Hell for him...."
However, the prohibition of nivul peh only applies when the subject matter is inappropriate. When appropriate (e.g. a doctor's visit) the prohibition of nivul peh does not apply.
In practical terms, terms (like the "f-word") that are inherently lascivious, in that they specifically refer to sexual topics in a non-respectful way (and would therefore never be used in an appropriate context), are indeed completely forbidden.
Terms of a scatological or similar nature would definitely fall into the category of "not clean" language and should therefore be avoided.
In addition, there is a general imperative of derech eretz (civilized behavior) which would demand that we avoid using language that is seen as generally offensive and crude. This would include all of the terms we have already discussed, as well as words that are seen, somewhat arbitrarily, as "curse words" in English (such as "hell" or "damn").