Yes, sign is playable
					...and is worth 7 points.
			
	
		
		
		
	
	Found in the following dictionaries
	Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Sign" Definition
        noun
        	
		A body manifestation that serves to indicate the presence of malfunction or disease.
		
	 
	
	    	
		A conventional figure or device that stands for a word, phrase, or operation; a symbol, as in mathematics or in musical notation.
		
	 
	
	    	
		A displayed structure bearing lettering or symbols, used to identify or advertise a place of business:  a motel with a flashing neon sign outside.
		
	 
	
	    	
		A portentous incident or event; a presage:  took the eclipse as a sign from God.
		
	 
	
	    	
		A posted notice bearing a designation, direction, or command:  an EXIT sign above a door; a traffic sign.
		
	 
	
			    phrasal-verb
        	
		Sign in  To record the arrival of another or oneself by signing a register.
		
	 
	
	    	
		Sign off  Informal   To express approval formally or conclusively:  got the Congress to sign off on the tax proposal.
		
	 
	
	    	
		Sign off  To announce the end of a communication; conclude.
		
	 
	
	    	
		Sign off  To stop transmission after identifying the broadcasting station.
		
	 
	
	    	
		Sign on  Informal   To enlist oneself, especially as an employee: "Retired politicians often sign on with top-dollar law firms”  ( New York Times).
		
	 
	
			    verb-transitive
        	
		To approve or ratify (a document) by affixing a signature, seal, or other mark:  sign a bill into law.
		
	 
	
	    	
		To communicate with a sign or signs:  signed his approval with a nod.
		
	 
	
	    	
		To consecrate with the sign of the cross.
		
	 
	
	    	
		To express (a word or thought, for example) by sign language:  signed her reply to the question.
		
	 
	
	    	
		To hire or engage by obtaining a signature on a contract:  signed a rookie pitcher for next season; sign up actors for a tour.
		
	 
	
			    verb-intransitive
        	
		To make a sign or signs; signal.
		
	 
	
	    	
	
			    verb
        	
		To place a sign on or mark by  .
		
	 
	
	    	
		To represent or indicate by a sign.
		
	 
	
	    	
		To affix a  to ratify or attest by hand or seal  .
		
	 
	
	    	
		To assign or convey formally .
		
	 
	
	    	
		To write down (one's name).
		
	 
	
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