57) It is obligatory to conceal one's private parts in the toilet and at all times from adult persons even if they are one's near relatives (like mother, sister etc.) Similarly, it is obligatory to conceal one's private parts from insane persons, and from children who can discern between good and evil. However, husband and wife are exempted from this obligation.

Now in case of bikini waxing as this is just a beatification of a body and not for a medical issue so a woman is not allowed show her body to other women if it has possibility of rise their sexual desire, otherwise she must cover her whole body this to be is that she must cover the private parts to all other than her Husband, however, if the other parts cause sexual desire, then she must cover those as well.