[Meaning] the anus/rectum. [sc. Named] from the fact that it pushes forward the [contents] of the stomach.[1]
And a proverb: "look into a dog's arse!"[2] This they used to say to those suffering eye trouble. Aristophanes in Acharnians [writes]: "blow 'the dog's arse' on the bone-pipes."[3] And elsewhere Aristophanes [writes]: "let someone summon Antisthenes without fail, for to judge by moans this man knows what the arse requires when it needs to shit. O mistress Eileithyia, may you never stand by and watch me being split apart, nor stoppered-up."[4] Meaning being overcome by the dung. Antisthenes [was] an effeminate physician. On the subject of Kleon Aristophanes says, "he had an arse of a chimney."[5]
The anus/rectum.
[sc. So called] from the fact that it sends forth.[6]