&gt; Because there&#x27;s functional as in only using pure functions (Haskell, ocaml) and functional as in access to higher order functions (JavaScript, erlang, clojure)<p>Or functional as having proper closures.<p>Or tail call elimination.<p>Or using immutable data, or immutable variables.<p>Or minimizing mutable state.<p>Or being decalrative.<p>etc...<p>;-)