epigyne

Etymology
From modern Latin epigynum, from +.

Noun

 * 1)  The external female sex organ in arachnids.
 * 2) * 1996: This [genital] area is inconspicuous in most adult males and in immature females, but in adult females of the majority of species it is modified into a variably shaped, more or less sclerotized structure called the epigyne. — Michael J. Roberts, Spiders of Britain and Northern Europe (Collins 1996, p. 16)