The word fuck can be used in so many ways.
that can be the only word in a sentence... for example: Fuck fucking fuck fuckers!!!
But it has many many meanings as well.
like some pervy jock guy in high school saying that he fucked a girl at a party and got her pregnant then fucked her best friend the next day. Then after that he went and fucked her mother!!!
it can also be used in a situation when you hurt youself or do something wrong and you think you were dumb.
for example: You got a simple problem like 2+2 and put =5... you are entitled to yell: "FUCK!!!"
or if you are walking by a guy you like (not the pervy jock high schooler) and you trip by falling over your feet then fall on your face and land in some water so it looks like you pissed yourslef... you definatly have the right to scream "FUUUUUUUUUUCK!!!"
so, there are some of the meanings of the word FUCK.
(i didn't just happen to come up with these things, they can happen... TRUST ME)