[duped]

The term might be a bit new now that we have some work that seeks to establish a formalism for it, but the concepts are very old.

A modern definition could be that ownership semantics define how aliases to data are created and shared. This includes things like variable binding and class members, but also encapsulates pointers and references - which have formal semantics in every language that uses them (and therefore, bake in ownership, even if it is implicit).

In systems programming languages like C and C++ the word "owner" and "ownership" are often used to describe which data structures and calling contexts are responsible for managing data lifetimes, since aliases to that data are used to control memory allocation and deallocation. The semantics are not baked into the language, but most software in these ecosystems has to be written with ownership in mind to be sound - and indeed, has been for many years, with that verbiage ("lifetime", "owner", etc).