In Clojure, something that is “seq”-able can be turned into an object (a seq) that implements an interface that can provide the first item of an ordered list, aka the head, and the rest of the items, aka the tail. As usual in Clojure, seqs and their methods provide various guarantees such as immutability.
The unfortunate part about the situation is that “seq” is pronounced “seek”. “Seq-able” sounds like “seekable”. Seekability, however, implies a completely different set of properties than a seq. Something that is seekable typically allows random access (access any member of the collection at a cost of O(1)) for example via multiplication of an index by an object size. The seq interface, meanwhile, is O(n) for random access even if the underlying data structure could support random access.
Thus, if you’re listening to a Clojurian speak, keep in mind that when they say “seek”, they’re really saying “seq”.