Bullshit is a commonly used English language expletive. It basically refers to nonsense.
Thought the term ‘bullshit’ is understood as one that developed recently, it actually dates back to the 17th century. Back then, the word ‘bull’ itself was used as a synonym of nonsense, while the evolved form of the word, i.e. bullshit, came into existence as late as the 20th century, in the year 1915 to be precise. If colloquial usage is taken out of the word, bullshit actually means the excrement of a bull, or a manure of sorts. This is also why the meaning of bullshit is so given, as excrement or manure is not of any use to people in general.
Usable as a noun or a verb, bullshit basically means that which is untrue, impractical, or unreasonable. It is something which cannot be believed at all, not even at face value. As a noun, the word would be used in the given form, but for using it as a verb, the suffix ‘ing’ has to be placed at the end of the word. The below examples illustrate the use of the word bullshit as a noun and verb respectively.
This is such bullshit.
Hey man! Don’t be bullshitting us this way.
The word bullshit is though used as slang and in retaliation to an improper conduct, it may also be euphemized, or put in a slightly polite and acceptable manner. For instance, the word might be shortened to bull, to indicate that the conversation is going off its course. Some people like to speak out or write only the initial letters of the word, i.e. BS, for such a purpose. The term may also be used by varying names in different countries. One such example is ‘bollocks’, which is equivalent to bullshit, but is used specifically in the UK and British English.
Therefore, the above was a brief description on the meaning of bullshit.