What is the meaning of percentile?

I am confused by the term percentile. Once my teacher told me that percentile means the percentage with respect to the score of the highest achiever.

This means that if in a competition I got $80$ out of $100$ and the highest score in that competition was 90 out of 100 then my percentile would be $\frac{80}{90}\ast 100=88.89$

So I got $80\mathrm{\%}$ and $88.89$ percentile.

I was believing that my above concept was right.

But when I see the definition of percentile on Wikipedia then I got something new (but I don't understand this definition) and then I thought that what my teacher told me was wrong.

Kindly tell me if my teacher right or wrong.

I am confused by the term percentile. Once my teacher told me that percentile means the percentage with respect to the score of the highest achiever.

This means that if in a competition I got $80$ out of $100$ and the highest score in that competition was 90 out of 100 then my percentile would be $\frac{80}{90}\ast 100=88.89$

So I got $80\mathrm{\%}$ and $88.89$ percentile.

I was believing that my above concept was right.

But when I see the definition of percentile on Wikipedia then I got something new (but I don't understand this definition) and then I thought that what my teacher told me was wrong.

Kindly tell me if my teacher right or wrong.