This question already has an answer here:
Can you use population to refer to a particular population? For example the population of women in Maths Class, from which we can take a sample to measure the height in order to make a judgement of the height of all the women in that class (i.e., the population).
This question is different from previous Population vs. sample questions, by addressing to the meaning and how the term "population" can be used. As I mentioned in the question: is it correct to say "population of women in Maths Class"? Or once you add some extra context to the term "population" it is no longer a population, but a sample, or something else.