Medlar

noun

1. Mespilus germanica, common medlar (now often Crataegus germanica)
2. Any tree of the genus Mespilus, now often Crataegus sect. Mespilus, including many species now in other genera.
3. Any of several similar trees that bear similar fruit
4. The fruit of such trees, similar to small apples
5. (derogatory, intended sexually) A woman or a woman's genitalia (as the fruit's appearance mimics an "open-arse")