Sentence:  She looked like the same old Molly, only more so, wearing Levis and an old cotton shirt with the <WSD>shirttail</WSD> out; she had a clothespin in her mouth and three or four more in the shirt pocket. 
Meaning of the word marked with <WSD> tags:  The single or split (then rather plural) bottom part of a shirt, below the waist, especially in the back, which, when not tucked into trousers or other vestment, hangs over the wearer's tail-end, like a tail.