Functor

Functor encapsulates the concept of a thing that can be mapped over.

trait Functor[F[_]] {
  def map[A, B](fa: F[A])(f: A => B): F[B]
}

Scala's syntax makes it more difficult to see here but what map is doing is transforming a function over values into a function over Functor values.

map: (A => B) => (F[A] => F[B])

Most programming collections admit a Functor so another way to name the concept represented is "changing the values of a collection into another type".