Yes, run is playable
...and is worth 5 points.
Found in the following dictionaries
Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Run" Definition
noun
A blemish caused by excessive paint flow.
A campaign for public office: She managed his successful senatorial run.
A continuous period of operation, especially of a machine or factory.
A distance covered by or as if by running.
A fall or slide, as of sand or mud.
adjective
Being in a melted or molten state: run butter; run gold.
Completely exhausted from running.
Having made a migration or spawning run .
Exhausted or winded from running.
Made from molten material cast in a mold .
verb-transitive
Computer Science To process or execute (a program or instruction).
Football To attempt to advance (the ball) by carrying it.
Games To clear (the table) in pool by consecutive scores.
Games To score (balls or points) consecutively in billiards: run 15 balls.
Metallurgy To melt, fuse, or smelt (metal).
idiom
Earth To pursue and successfully capture: Dogs ran the fox to earth. The police ran the terrorists to ground.
Foul To come into conflict with: a pickpocket who ran foul of the law.
Foul To run into; collide with: a sloop that had run foul of the submerged reef.
Gas Slang To falter or come to a stop because of a lack of capital, support, or enthusiasm.
In the long run In the final analysis or outcome.
verb-intransitive
Informal To leave; depart: Sorry, I have to run.
Nautical To sail or steer before the wind or on an indicated course: run before a storm.
To accumulate or accrue: The interest runs from the first of the month.
To be in operation: The engine is running.
To be present as a valid accompaniment: Fishing rights run with ownership of the land.