What is anal sex? Anal sex is an act between two consenting individuals, where the anus is stimulated in some way. It is important that this practice is done safely, so read on to learn about all the things you can do to make anal sex an enjoyable and safe experience! The only reason you should have anal sex is because you really want to. A: Anal sex means inserting the penis in your partners anus. The anus is the tail end of the digestive system which is not part of the reproductive system and is not ideally designed for sex. The anus and rectum are home to the residue of the digestive system - faeces, bacteria, and viruses. Definition of anal adjective in Oxford Advanced Learner's Dictionary. Meaning , pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. Anal sex is a sex act performed on the anus. Anal sex can involve a penis inserted in the anus, oral stimulation, of the anus, using fingers for penetration and using different objects for stimulation.