From Greek auto- and telos, meaning self- and goal or end.
A process or practice that has no function or purpose other than itself.
If you and I talk only for the purpose of having a conversation, refusing to subordinate this pleasure to any external purpose, our conversation is autotelic.
This term is usually used to characterize the poetic use of language, and more generally, its artistic use by any intermediary.
Hence Roman Jakobson states that an aesthetic message (as an example he uses Archibald McLeish’s poem Ars Poetica) has no function other than to serve itself, except the way it uses the innate abilities of some intermediaries (language, in the case of Ars Poetica)