'Woman' and its plural 'women' are, strictly speaking, nouns. I think that it is only in the last 30 years that they have been used as adjectives in place of 'female'. What is wrong in your sentence is 'women parliamentarian'. 'Parliamentarian' implies only one person, in this case, one woman; therefore 'woman parliamentarian'—though it's much better to write 'female parliamentarian'. There are hundreds of nouns showing gender: mother, sister, uncle, hen, ****** etc.; but far fewer gender-laden adjectives: manly, masculine, feminine, uncle, for example. [This is interesting: the computer program has replaced the name for a female dog with asterisks.]