Presented without comment: Our English anus comes to us intact from Latin, where it had its present meaning; but Latin bequeaths us another anus, that I learned about from Norman Schur's 1000 Most Challenging Words: anile, meaning to behave like an old woman, comes from the Latin anus, which was their word --entirely unrelated to the other, Schur assures us-- for 'old woman.'
Alright, now for the comment. If memory serves, the Spanish name for the ring finger is dedo anular. I don't know if it's undue influence of Captain Beefheart's song 'Korn Ring Finger*,' but that name looks to me a lot like 'anal finger.' Well, wouldn't you know it, that first Latin anus does in fact also mean 'ring'; I presume the body part was so named for its shape.
I mean no disrespect to old women by writing about this. Pity the word anile isn't so polite. It does have one polite application, I suppose, though the politeness will only be within your mind: if you're unsettled, as I am, whenever someone describes themselves as 'anal' as a shortening of Frued's somehow even less pleasant 'anal retentive' --a concept which deserves none of its currency, I hope you'll agree-- you can pretend they have in fact said 'anile,' even though neither the pronunciation nor the meaning is quite right.
*it's a bonus track added to the 1999 release of Safe As Milk