information:extraction, structural:expansion
Sources and etymology

Different languages and cultures construct swear words and phrases from violations of different social taboos, and many names for offensive language derive from the source topic.

Profanity in the religious sense involves desecration of the sacred, whether by blasphemy or other words causing religious offense, such as taking the Lord's name in vain. Many religions include the notion of casting a curse, which is both disrespectful and intentionally harmful, and is often also taboo. Hence curse phrases like "God damn it to hell", which can be shortened to just "damn". To swear an oath in a highly religious society often involved invoking a sacred entity or event; this act has evolved into profanity. For example, "I swear to God" can be used as an intensifier or to express strong emotion in a potentially offensive way. An oath can also be shortened to simply saying the name of a holy figure, for example yelling "Jesus!" when surprised.

Many cultures have taboos surrounding human sexual activity, and obscenity sometimes refers specifically to depictions or acts related to sex. Some obscenities simply mention sex acts or genitalia or erogenous zones. They can be turned into personal insults by involving the target in the sex act (e.g. "fuck you!") and can be intensified by adding details that invoke disgust or violate more taboos, such as the involvement of family members or animals. Spanish profanity often involves references to prostitution or homosexuality. The term "bastard" invokes a taboo against children born out of wedlock. Swear words like puta (whore), bitch, maricón (faggot), and bastard are also slurs which refer to specific groups of people; their use is sometimes challenged by advocates of social equality and those who oppose the underlying taboos.

Foul language is also derived from taboo bodily functions or body parts, especially those which produce disgust, such as the foul odor of excrement. Specific words referring to the same thing can be marked as offensive or polite arbitrarily; for example, " shit " is considered offensive, whereas "poop" is informal but inoffensive, and " feces " while referring to a disgusting object is considered appropriate for formal and polite contexts, such as scientific discussion. Likewise, " asshole " is usually a derogatory term for a person, but " anus " is formal and scientific.

The older sense of "vulgar" is "common"; for example, Vulgar Latin is the colloquial language of the common people of Rome, which does not carry a connotation of being offensive. Terms like "vulgar" and "colloquial" can be used as euphemisms to describe speech which is not only informal but also offensive. Vulgarism refers to a linguistic error typical of an uneducated speaker.

An expletive in the general linguistic sense is a word or phrase that is a grammatical placeholder or extraneous, including auxiliary verbs like "do" (in Standard English), and expletive pronouns like "it" and "there" (e.g. "there is a man at the door"). Another subcategory, expletive attributive, is an adjective or adverb used as an intensifier. Many of these are swear words, but not all.