Theme week! -- medical terms. I'll try not to get too disgusting, but, well, medical terms.
fistula (FIS-choo-luh) - n., an abnormal passage that connects an abscess or hollow organ to the body surface or to another hollow organ.
Can be a pathology thing, such as a cyst that opens to the air, or may be surgically created to permit passage of fluids or secretions, such as here:

Thanks, WikiMedia!
Or to drain an abscess. The term has been around since the 14th century, from Latin, where it originally meant pipe and later also meant fistula as well as ulcer, of uncertain origin (several are proposed).
---L.
fistula (FIS-choo-luh) - n., an abnormal passage that connects an abscess or hollow organ to the body surface or to another hollow organ.
Can be a pathology thing, such as a cyst that opens to the air, or may be surgically created to permit passage of fluids or secretions, such as here:
Thanks, WikiMedia!
Or to drain an abscess. The term has been around since the 14th century, from Latin, where it originally meant pipe and later also meant fistula as well as ulcer, of uncertain origin (several are proposed).
---L.