Yes, back is playable
...and is worth 14 points.
Found in the following dictionaries
Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Back" Definition
noun
A part that supports or strengthens from the rear: the back of a couch.
A shallow vat or tub used chiefly by brewers.
Sports A player who takes a position behind the front line of other players in certain games, such as football and soccer.
Sports This playing position.
The analogous dorsal region in other animals.
phrasal-verb
Back away To withdraw from a position; retreat.
Back down To withdraw from a position, opinion, or commitment.
Back off To retreat or draw away.
Back out To fail to keep a commitment or promise.
Back out To withdraw from something before completion.
adjective
Being in a backward direction.
Being owed or due from an earlier time; in arrears: back pay.
Distant from a center of activity; remote.
Linguistics Pronounced with the back of the tongue, as oo in cool. Used of vowels.
Located or placed in the rear: Deliveries should be made at the back entrance.
verb-transitive
To adduce evidence in support of; substantiate: backed the argument with facts.
To cause to move backward or in a reverse direction: Back the car up and then make the turn.
To form the back or background of: Snowcapped mountains back the village.
To furnish or strengthen with a back or backing.
verb-intransitive
To move backward: backed out of the garage.
To shift to a counterclockwise direction. Used of the wind.
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