For work-place specific gender-neutral politically-correct terms refer to the answer by @third-news. Otherwise, as elliot frisch has suggested, lady is the term you want. But in my opinion, if you're …

Unfortunately, when i google, i'm getting a bunch of low-q Ladies is the plural form of lady, so the apostrophe goes to the right - ladies'. If you are wondering why we don't write ladies's, it is because ladies is one of the exceptions, along with girls', parents', … In britain it has largely become a matter of taste and personal preference as to which of chairman, chairperson, or chair are used. Chairwoman would be unusual unless it were of an organisation …

Chairwoman would be unusual unless it were of an organisation …