Yes, arm is playable
					...and is worth 6 points.
			
	
		
		
		
	
	Found in the following dictionaries
	Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Arm" Definition
        noun
        	
		A branch of a military force:  infantry, armor, and other combat arms.
		
	 
	
	    	
		A part similar to a human arm, such as the forelimb of an animal or a long part projecting from a central support in a machine.
		
	 
	
	    	
		A relatively narrow extension jutting out from a large mass:  an arm of the sea.  See Synonyms at branch.
		
	 
	
	    	
		A weapon, especially a firearm:  troops bearing arms; ICBMs, bombs, and other nuclear arms.
		
	 
	
	    	
		An administrative or functional branch, as of an organization.
		
	 
	
			    idiom
        	
		An arm and a leg  Slang   An excessively high price:  a cruise that cost an arm and a leg.
		
	 
	
	    	
		Arm in arm  With arms linked together:  They walked across the beach arm in arm.
		
	 
	
	    	
		Up in arms  Extremely upset; indignant.
		
	 
	
	    	
		With open arms  With great cordiality and hospitality.
		
	 
	
			    verb-transitive
        	
		To equip with weapons:  armed themselves with loaded pistols; arm a missile with a warhead; arm a nation for war.
		
	 
	
	    	
		To equip with what is needed for effective action:  tax advisers who were armed with the latest forms.
		
	 
	
	    	
		To prepare (a weapon) for use or operation, as by releasing a safety device.
		
	 
	
	    	
		To provide with something that strengthens or protects:  a space reentry vehicle that was armed with a ceramic shield.
		
	 
	
			    verb-intransitive
        	
		To prepare oneself for warfare or conflict.
		
	 
	
	    	
		To supply or equip oneself with weaponry.
		
	 
	
			    abbreviation
        	
	
	    	
		Adjustable rate mortgage.
		
	 
	
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