Grammar

How one word does the work of a dictionary

Most swear words are stuck in one job. Fuck is unusual because it will do almost any job in a sentence, including one that no other English word can do.

Every part of speech

RoleExampleNote
Transitive verbHe fucked her.The original, literal sense.
Intransitive verbThey fucked.
Verb, figurativeThe printer's fucked. Don't fuck with me. You fucked up.Ruin, meddle, fail. The dominant modern senses.
NounI don't give a fuck. What the fuck? A good fuck.Also as a unit of caring, as in "fucks to give".
AdjectiveThe fucking car won't start.Almost never literally sexual.
AdverbIt's fucking freezing.Pure intensifier.
InterjectionFuck!Pain, surprise, fury, delight.
InfixAbso-fucking-lutely. Un-fucking-believable.See below.
Phrasal verbsfuck off, fuck up, fuck about, fuck around, fuck overEach with a distinct meaning.

The infix, which English is not supposed to have

English builds words with prefixes and suffixes, not by inserting material into the middle of a word. There is one exception: expletive infixation. You can say abso-fucking-lutely and every native speaker will accept it. You cannot say ab-fucking-solutely, and everyone will hear that it is wrong.

The linguist John McCarthy worked out the rule in 1982. The expletive goes immediately before the syllable that carries the main stress, and only if there is at least one full foot of the word to its left. So: Massa-fucking-chusetts, fan-fucking-tastic, Cinde-fucking-rella, but never Mass-fucking-achusetts. Nobody is taught this. It is one of the clearest demonstrations that speakers carry a detailed, unconscious model of English stress, and the F-word is the standard textbook example.

Losing its meaning, keeping its force

Linguists call it semantic bleaching: a word is used so often for emphasis that its literal content drains away. In "fucking freezing" nobody is thinking about sex. The word has become a grammatical device for turning the volume up, in the same way "very" and "terribly" once carried real meaning and now barely do. What makes fuck different from "very" is that the taboo has not bleached along with the meaning. It still carries a shock even when it carries no sense, and that gap between meaning and force is why it is so useful and so easy to overuse.

Fixed phrases

A short and far from complete list of constructions in which the word has a settled, idiomatic meaning:

Softened forms

Because the word is taboo, English has grown a whole set of stand-ins: eff, effing, the F-word, frig, frick, feck (Irish, and technically a different word), fudge, flip, freaking, fug, F***, WTF and AF. Every one of them works only because the listener silently fills in the real word, which is a reasonable argument that the euphemism and the original are not as different as their users like to think.