You round the corner and see <<print setup.orcDescriptions.random()>> orc!
To convert the above into a <<widget>> simply do the following:
a. Add a new Passage to your story and assign it a widget tag, this can now be used to store all your story's widget definitions. The actual name of this Passage is not important, I generally name mine Widgets for convenience.
b. Add the following TwineScript to this new Passage, it defines a widget named OrcDescription which outputs a randomly selected item from the setup.orcDescriptions Array.
c. You can use the new <<OrcDescription>> widget like so.
You round the corner and see <<OrcDescription>> orc!