Reading a book last night where a woman is described wearing a dress up to her pudenda. What's that? Had a good guess but still compelled to look it up. So, if you use it, don't show your ignorance and mix the uses of plural and singular.
Main Entry: pu·den·dum
plural pu·den·da \-də\ the external genital organs of a human being and especially of a woman —usually used in plural.
Etymology: (date 1634) New Latin, singular of Latin pudenda, from neuter plural of pudendus, gerundive of pudēre (GET THIS) to be ashamed.