DuckCorp Dico

Found one definition

1.                 From Japanese-English FreeDict Dictionary ver. 0.1:
                   
   
   
                   
                     
   窪 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, 凹 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, くぼ /kˈɯᵝbo̞/
   1. (noun (common) (futsuumeishi))
   hollow, cavity, sunken place
   2.
            Note: archaismvagina, female genitalia