Not really either. Conj acts on collections (which can be lists, vectors, sets or hash maps), and adds the second and subsequent arguments to the collection in

Not really either. Conj acts on collections (which can be lists, vectors, sets or hash maps), and adds the second and subsequent arguments to the collection in a type-dependent way. For a list, your hunch is correct, in that it's a bit like a reversed-argument 'cons', except that you can have add more than one item to the list; e.g. (conj '(:a :b :c) :d :e :f) returns (:f :e :d :a :b :c)