Yes, paper is playable
...and is worth 11 points.
Found in the following dictionaries
Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Paper" Definition
noun
A collection of letters, diaries, and other writings, especially by one person: the Madison papers.
A formal written composition intended to be published, presented, or read aloud; a scholarly essay or treatise.
A material made of cellulose pulp, derived mainly from wood, rags, and certain grasses, processed into flexible sheets or rolls by deposit from an aqueous suspension, and used chiefly for writing, printing, drawing, wrapping, and covering walls.
A piece of written work for school; a report or theme.
adjective
Existing only in printed or written form: paper profits; a paper corporation.
Of or relating to clerical work: paper duties.
Planned but not realized; theoretical.
Resembling paper, as in thinness or flimsiness.
idiom
In paper With a paperback binding; as a paperback.
On paper In theory, as opposed to actual performance or fact: It is a good team on paper, but its members play poorly together.
On paper In writing or print.
phrasal-verb
Paper over To downplay or gloss over (differences, for example), especially in order to maintain a nominal, apparent, or temporary unity.
Paper over To put or keep out of sight; conceal: paper over a deficit with accounting gimmicks.
verb-transitive
Slang To issue free passes for (a theater, for example).
To construct (something) in haste and with little forethought: papered together a new coalition of political convenience.
To cover, wrap, or line with paper.