Is the word "stool" an informal word or a formal word?

[KUROMY]

Is the word "stool" an informal word or a formal word?
I think it is a kind of formal word, especially a medical word.
It is used in several academic papers and articles, and also doctors like using this word when they want to talk about status of patients' excrements.
However my English teacher(not native speaker) said that the word stool is an informal word, like poo and I should use "feces or excrement" as formal language.
So I told him that I think it looks like a formal word than informal word because basically it is a specialized word.
Then he said that "Native speakers" use the word stool in informal conversation as using phasal verbs like"have a stool", "after stool", or "go to stool".
I have never heard of those kind of expressions before.
Is he correct?

 

[bhaisahab]

No, he is not correct. We don't use these expressions "have a stool", "after stool", or "go to stool".

 

[Tdol]

Then he said that "Native speakers" use the word stool in informal conversation as using phasal verbs like"have a stool", "after stool", or "go to stool".

I agree with Bhaisahab, and, furthermore, I have only heard people use the term stool when talking to a doctor. Faeces and excrement are used in some formal contexts, but that does not make stool colloquial.

 

[bubbha]

I've only ever heard "stool" in a medical context, such as a "stool sample". I've never heard anyone use it in a slang or informal sense.

 

[GoesStation]

Your teacher may have misunderstood the common expressions after school and go to school.

Also be aware that another word, also spelled stool and pronounced the same, is pretty common. It means a piece of furniture for sitting on, without armrests or a back.