Otherwise known as: on the four-letter (swear) word.
These are the words that our society deems verbotten–we cover the ears of children when they are uttered in a movie and do not dare to say them around our grandmothers for fear of a stern look. There are at least seven that cannot be uttered on the air or the FCC has a shit fit.
What they are: shit, piss, fuck, cunt, cocksucker, motherfucker, and tits. With the exception of cocksucker and motherfucker they are all four-letter, one syllable words. To that list I’d like to add two more–bitch and ass(hole).
My theory why most of the basic cuss words are one-syllable words is simple: they are words that can be spit at someone. They don’t require forethought or any other kind of complex thinking. Just something one can say in anger or frustration–emotions that generally do not coexist alongside rational forethought. Insults are scatological and/or sexual in almost every language
As for the longer words, well, the only reason I can think of for their existence is that they are combinations of shorter words–cock and suck, mother and fuck and are therefore easier than non-combined words (can’t think of the linguistic term right now) to say. Anybody have an alternative suggestion?