Other forms: fucking; fucked; fucks
Fuck is one of the most common words in English — it's also one of the most offensive. Its main meaning is "have sex," but it has hundreds of other uses.
This slang term for sexual intercourse is not a word to be used lightly — it's an obscenity that, if used on some television networks, could cost the person who "dropped the f-bomb" thousands of dollars. Despite all the people who don't want to hear it, fuck is one of the most common obscenities, and can be used as a noun, verb, adjective, and adverb. It's often used as a modifier to add emphasis to another word, as in "that's so fucking stupid!"